Bare-foot übergeek and Facebook founder Mark Zuckerberg today has more to worry about than how many zillions to accept for his social-networking behemoth. Zuckerberg is in court fighting a lawsuit that claims he stole the idea and the source code for Facebook.

Zuckerberg has been accused of stealing the Facebook concept from three former Harvard students who recruited him to work on ConnectU - coincidentally, a social-networking website, but a rather less successful site than Facebook.

Cameron Winklevoss, Tyler Winklevoss and Divya Narendra filed suit three years ago claiming that Zuckerberg stole the ConnectU idea, source code and business plan for his own Facebook site. They claim that Zuckerberg even worked intentionally slowly on ConnectU to give himself time to get Facebook online first. Zuckerberg denies the accusations.

Facebook currently adds a staggering 150,000 members a day. It's very much the social-networking site du jour, as a glance at my inbox will quickly attest. So popular is Facebook that rumours abound that Zuckerberg has turned down offers of $750m from Viacom and $1bn from Yahoo.

Facebook's most popular network - our very own London - now has almost 800,000 members, including your author. Some of them occasionally spend time on other websites. (But not many.)

But for all that, Facebook isn't a particularly original idea. Social-networking sites proliferate, and Facebook's massive popularity is down to a melange of factors. It's a combination that definitely includes smart design and simple functionality, but also owes thanks to Facebook's increased visibility after students blogged throughout the Virginia Tech massacre, and its generally faultless right-time-right-place timing.

Part good planning, part good fortune, then. And the nature of these websites is such that the winner takes it all.

Even if the plaintiff's case enjoys a modicum of truth, then, there's no way of knowing that ConnectU would have ever been more successful than it is. Which isn't the point, I accept, but does suggest an element of sour grapes. Still, it's good publicity for everyone, I suppose.