Apple's move to open up Siri to third-party developers looks set to be the big news today, according to FT sources. Read our curtain-raiser piece we wrote last week looking at where Siri stands today and how Apple might be able to catch up with the likes of Amazon's Echo.
The event should start in about 10 minutes. In the meantime, as has become traditional at events since Apple Music launched a year ago, we are listening to Zane Lowe on Beats 1 radio station here at the Bill Graham Civic Auditorium.
As you might have heard, Microsoft paid $26bn to buy LinkedIn today. But don't worry - Apple isn't falling behind in social media. It has a special WWDC Snapchat filter!
The lights are dimming... The Apple logo is resplendent in ASCII-style flickering code on the stage right now.
It's worth noting that it is unusual for Apple to shift the WWDC keynote outside the Moscone Center, where the rest of the developer sessions are being held. Bill Graham Civic Auditorium was the venue for last September's iPhone 6S and iPad Pro launch.
Here's Tim Cook. He starts off by talking about the shooting in Orlando, offering "deepest sympathies" for what he calls a "senseless unconscionable act of terrorism and hate aimed at dividing and destroying."
Apple celebrates its diversity, he says, asking the audience to stand for a moment of silence for the victims. And then, in a sudden change of tone, we are back to WWDC - "we have a jam packed morning for you."
Here's the first big stat of the day: Apple now has 2m apps on the App Store, up from 1.5m a year ago, which have been downloaded 130bn times.
"The App Store is the best business opportunity - we are about to pass $50bn paid directly to developers," says Tim Cook.
Talking of app developers: Apple already came out with a big piece of the WWDC news in advance, when it said last week it was going to give some developers a bigger slice of the revenues from selling apps.
Cook is going though Apple's big four platforms: the Mac, iOS, WatchOS and tvOS.
"We love creating products that change the world - but we can't do it alone," says Cook. "You are a part of everything that we do - and everything that we will do going forward."
We are starting with WatchOS and here comes Kevin Lynch.
WatchOS 3 is making big changes to how users navigate the Watch. Apps will launch 7 times more quickly (a big pain point for users and developers alike).
Replying to text messages is streamlined through a new "scribble" mode where writing letters straight on the screen is converted into text. There's a new activity-centric watch face that shows how much you are exercising.
The side button, which previously was only used for accessing contacts, now brings up a row of apps in a new "dock".
That looks a big improvement on the honeycomb grid of tiny app icons and the clunky "glances".
The first nod to Apple's most important market: that new "scribble" input mode works in English and Chinese.
Scribbling letters on a tiny screen still seems backward-looking, somehow. Wasn't it meant to be all about voice and Siri by now?
Apple Watch is getting the ability to share activity with friends - a competitive dimension that has been one of Fitbit's biggest assets. That could help to open up the corporate wellness market to Apple a little, too. It also brings Apple Watch a bit of the network effect that was supposed to happen with its Watch-only messaging, which fell almost entirely flat.
Apple is pushing deeper into the health space with a new Watch app, Breathe, which guides you through a guided deep-breathing session as it tracks your heart rate. instead of a standard alert, you can tell the Watch to remind you to "take a minute to breathe."
This is just the first in a series of health and fitness updates for WatchOS, Apple says - interesting that it is focusing these on the Watch rather than making them available to the much larger group of iPhone owners.
"It's going to feel like a whole new Watch," promises Kevin Lynch. The update will be out for developers soon and everyone else in the autumn.
Now, he hands over to services chief Eddy Cue to talk about tvOS.
Kevin Lynch called the new Watch OS a "giant leap forward".
Not sure it lives up to that claim, but definitely some simplifications that make should make it easier and more enjoyable to use.
So far, the Apple TV updates seem fairly incremental. We are seeing a new Apple TV remote app, live viewing and expanded Siri search functions. There's also a new app, Single Sign-On, which does away with all those individual login screens for each individual app.
And that's Eddy Cue's turn over (for now), here comes Craig Federighi (Apple's senior vice president of software engineering) to talk about the Mac.
Mac OS X, a 15-year-old name, is now macOS, bringing its branding into line with the rest of the Apple software platforms.
In keeping with its recent Californian branding, the latest generation of OS X, or rather macOS, is called Sierra.
Federighi is going through some of the new "Continuity" features that let you switch easily between Mac and iPhone or iPad.
There are oohs in the audience for "Universal Clipboard" which lets you copy something on your iPhone and paste it into a document on your Mac.
Look out PayPal: Apple Pay is coming to the web, using a paired iPhone (or Watch) to authenticate the transaction using Touch ID. Apple Pay is coming soon to Switzerland, France and Hong Kong, adds Federighi.
A slightly robotic female voice echoes through the room: "Hi, it's me. It sure is great to be on the Mac. How about a demo?"
Yes, it's Siri and she/it is coming to the Mac. You can play music, search the web, bring up recent files, and of course make slightly lame jokes.
Watching Federighi demo Siri working on a Mac makes you think of when Microsoft put Cortana on Windows 10 machines recently.
All very impressive, but not clear yet that people actually want to talk to their laptops.
Now, Federighi is turning to iOS 10.
"IOS 10 is a huge release for developers and the biggest release ever for users," he says.
First, we have a redesigned lock screen with richer notifications and extra use of 3D Touch. There are also new new home-screen shortcuts.
Slide over from the right to access the camera, slide over the other way to access widgets such as Siri app suggestions or News, Calendar etc. Google Now style live Widgets are also a new addition.
As the FT (and many others) reported: "We are opening up Siri to developers."
If listening to Siri on Mac was meant to make us think back to the original Macintosh launch in 1984, it fell a bit flat. Back then, Steve Jobs pulled Mac out of a bag, plugged it in and ran a demo. Mac's first words: "Hello, I am Macintosh. It sure is great to get out of that bag." (Cue mayhem from enthusiastic audience).
These days, hearing a computer talk seems very pedestrian.
Siri can be used in messaging, calling an Uber (or Didi in China, in which Apple just invested $1bn), or even making a payment.
It also has more contextual awareness in Messages (eg, if someone asks for John's email address, it pulls those details from your Contacts book as a suggested response).
Did I hear Federighi come up with the first mentions of "deep learning", to describe how Siri anticipates what you're trying to do and preempts you?
At Google's I/O developer conference last month the talk of deep learning and AI was almost a drumbeat.
Apple really needs to show it can master AI as well as Google.
Federighi describes how Apple is using deep learning to organise and surface photos - much of what he's describing echoes what Google has already down with its own photos app, which has been one of the most striking applications so far of its own AI.
Eddy Cue is back to talk about maps - another area where Apple is playing catch-up with Google.
For instance, he shows off how maps can show upcoming traffic conditions, just as Google does. But without Waze, the traffic app that Google uses to collect real-time road conditions, will the information be as up-to-date?
Now, Apple Music: a redesign "from the ground up", says Cue - even though it hasn't even been out for a year yet and is being hailed by the company as a great success, with 15m subscribers so far.
The first version of Apple Music came in for plenty of criticism over its muddled interface. And Connect, a social feature that was meant to act as a new channel for bands to connect with their fans, fell flat.
The new interface looks a lot cleaner, and the navigation through recommendations and browsing look more straightforward.
Apple has added subscriptions, so you can read news services you've subscribed to from inside the app.
Cue didn't spend much time on that, it seemed very cursory, before moving on to HomeKit - the software for controlling your home.
Federighi is back, and he's showing off a new Apple app called Home: a central place to control lights, the front door lock, whatever. It's a new control panel for the home. It's also available on iPads and the TV.
Next: the phone (yes, it's still a phone).
One interesting new feature: an automatic transcription service that will produce a text version of a call.
Sounds like a very useful feature, but Apple says it's in beta, the usefulness will depend entirely on the qualits of the speech-to-text
On to messsaging. Emojis!
There's sometimes a problem when you get to the end of a message and realise you're light on "emojification", says Federighi.
Answer? tap on the emoji button after you've written and it will highlight all the words that could be expressed as emojis instead. Hey presto!
Many of the new features in messaging are visual, such as including handwritten notes or being able to make some responses much larger than others.
There was also a brief mention of a way of speeding up responses with an auto-suggest feature, though that was played down: Google claims it has a much more advanced version of this, which it is calling instant replies, in its own new messaging app, Allo, which has yet to be launched.
Like Facebook and Google, Apple is also looking at messaging as a new computing platform. iMessage apps are a way for developers to add their own experiences: Federighi does a demo in which he orders food through the DoorDash food delivery service while in a conversation.
Other examples of third-party apps and content that are can be used with iMessage: buying tickets for an event, and extra stickers and GIFs.
Federighi has now got to the all-important issue of privacy.
"In every feature that we do, we carefully consider how to protect your privacy. With apps like FaceTime, Messages and HomeKit we make sure we use end to end encryption by default.. When you do searches on the internet, we don’t build any user profiles."
He makes much of "differential privacy" - the challenge making it easy for users to share information with the people they want to while making it totally private.
Apple called in the leading expert, he says - no names, though - and was told it was world class on this point.
Tim Cook is back on stage to wrap up. He's talking about Swift, the new programming language that Apple introduced at its developer conference two years ago.
Apple is using Swift to create a new programming tool called Swift Playground, aimed at teaching children how to code.
Swift Playground is the kind of demo you expect at a conference like this, but with a twist. Not the usual developer dashboard, but something designed to be intuitive and easy for children.
I wonder how many people in the audience wish they'd been able to start that way. Apple's trying to catch them young these days.
Cook: "We believe coding should be a required language in all schools."
One thing Apple never fails at are the motivational videos. The one that caps the Swift demo is no exception, as adults and children line up to talk about how they want to use this new tool to change the world.
That gives Cook the cue for his final comments.
"At Apple we believe that technology should lift humanity, and enrich our lives."
With that - and a claim that the latest iOS is "the mother of all releases" - he brings things to a close.
Anyone who's followed Apple events for a while will have got so used to the "one more thing" - the extra thing at the end that turns out to be the biggest news of the day.
But Cook isn't that kind of showman, he prefers to end on an uplifting moment like this.
After the emotional start to today's event, with the moment's silence for the Orlando shooting, it was an effective way to end things.
With four software platforms to show off and plenty of design changes and new features, it was easy to get lost in the flood of detail.
One thing that stood out was iMessage: like Facebook and Google, Apple has its sights set squarely on this as a new battleground for user attention.
It will be a battle fought with AI and emojis.
Apple has opened up Siri (which was expected) and iMessage (which was not) to developers for the first time, as the battle for developer attention moves beyond the App Store.
Apple got an early lead with Siri and has a captive audience for iMessage. But when it comes to voice-controlled assistants, Amazon and Google have jumped ahead with its Echo device, while Facebook has taken a lead in messaging.
As with Google's own developer conference last month, today's Apple event left the impression of a company scrambling to keep up with all the new directions computing is taking as it moves beyond the app world.