Since Facebook sent out invites to an event at its California headquarters this evening there have been several rumours about what the company plans to announce. They range from speculation about a major move into hardware, perhaps by launching a Facebook phone, to more mundane rumours about a minor new service, such as an iPad app for Facebook messages.

The company has been tight-lipped. The technology industry is gradually embracing the Apple approach to launching a new product - develop in secret, build anticipation by holding a launch event and then make the big reveal in the glare of the world's media. For maximum impact, the new product should be available as soon as possible after the launch even