The potted biography that Google provides for Sergey Brin, the company's co-founder, notes rather charmingly that he is "currently on leave from the PhD program in computer science at Stanford University". Given that Mr Brin is now thought to be worth more than $12bn (£6.4bn), one wonders whether he will ever get around to handing in his dissertation.

Google's nod in the direction of Stanford is, however, entirely fitting. Mr Brin met Larry Page, Google's co-founder, when they were both graduate students at Stanford and together they worked on the project that became Google. Yahoo, Google's arch rival, has a very similar history. Jerry Yang and David Filo, its founders, also met as graduate students at Stanford.