What have Barack Obama, Andy Murray, Downing Street and Britney Spears got in common? Not a lot. Except they all use twitter.com as a means of instant communication. Twittering is on a roll, even being mentioned on primetime television. Wherever I go in the social-networking community, it is rampant – everyone seems to be exchanging short messages about anything from breakfast, breaking news, a new website, to participating in a conference remotely. Israel used it as part of its Gaza war propaganda machine. For my colleagues in Technology Guardian, it has become almost a life-support machine. Yet when I move out into the rest of the world, hardly anyone has even heard of it. So what’s going on?