The Web security firm Barracuda Networks has surveyed Twitter use and determined that only about one-quarter of registered users are active. The suggestion is that Twitter is more of a news feed than a social network.

The study found that 73 per cent of users had Tweeted fewer than 10 times. And only 21 per cent had Tweeted 10 times, followed 10 and been followed by 10.

The study's author concludes that many on Twitter simply signed up to follow their favourite celebrities. Now that most celebrities have started Tweeting, the service doesn't have the same growth potential.