This morning’s Observer column…

To the old question: what are friends for? we must now add: how much are they worth? This is topical because rumours abound that Microsoft is contemplating buying a stake in Facebook, the social networking site. The really interesting bit is the arithmetic. Microsoft is supposedly contemplating paying between $300m (£147m) and $500m for a 5 per cent share. If true, this suggests that its advisers put a value of between $6bn and $10bn on Facebook. Google is also reported to be sniffing around, raising the prospect of a bidding war for a website which essentially enables people to post embarrassing photographs and impress acquaintances with accounts of their busy lives…