According to the folks over at Sourcewire, Facebook is now the most popular social-networking site in the UK, eclipsing the previous most-visited champ, MySpace, for the first time.

Interestingly, though, Second Life, the 3D virtual internet world, keeps using plugged in the longest.

Microsoft is rumoured to be purchasing a five per cent stake in Facebook for around £200m, valuing the company at somewhere in the region of £4bn. Is the new dot.com bubble about to burst, we wonder.

How many of you regularly participate in social-networking sites, and which is your favourite?