Gideon Rachman's blog: I have always found the idea that new media would somehow kill off old dictatorships unconvincing. The Chinese government seems to have coped perfectly well with the rise of the internet. Still, events in Iran have given new life to this theory. The use that the Iranian opposition has made of social networking sites and, in particular, of Twitter, has excited lots of interest.

On Tuesday the State Department even asked Twitter to delay an update of its service, so as not to disrupt the role the micro-blogging service is playing in allowing the Iranian opposition to communicate with each other. (Note for my mother: you can post tiny little updates on to a Twitter site, instantly, using a computer or your mobile phone - provided the "tweet" is no more than 140 characters long.) Some people have now predictably dubbed this the "Twitter revolution".