Users reply by either by tapping them in on a computer, or sending them in via text message.

“I’m currently researching vulnerability management,” is the news from a chap called Nathan, while “Browsing the web” is the somewhat redundant update from David in Toledo.

If you sign up, you can be notified of your friends’ movements, thoughts and sandwich fillings – Twitter’s founder, Evan Williams, claims that it will become “the pulse of society, the first place people go to share information”.

But, for many of you, this distillation of blog-ging into a single sentence is the absurd culmination of social networking. “I’m tired of receiving invitations to join websites with ‘friends’ and ‘updates’,” writes Keith Hunt. “It’s a perfect example,” emailed Tom Wetheredge, “of how the internet can keep us too connected.”

Twitter can fire off an SMS to your mobile whenever your friends update, which can feel like being electronically harrassed. In the US, where many have to pay to receive a text, mobile companies are coining substantial sums as a result and, even in the UK, sending updates to Twitter can be charged at a premium rate. As Josh N says, “It’s fantastic if you relish a lack of privacy and enjoy running up phone bills. But in a good way.”

If you cut your mobile phone out of the loop and check for updates online, the service is free, and can even be fun: the latest World Cup cricket scores appear regularly; someone has made a valiant attempt to keep users updated with London Underground delays; and even 2008 Presidential hopeful John Edwards is posting messages as he pinballs around the USA.

It’s also the perfect receptacle for idle thoughts, according to writer Leila Johnston. “Blogs are overrun with tedious details,” she writes. “Here, the dullards are gagged after 140 characters.” One user, at twitter.com/rhodri, is finding it addictive – at least for the moment.