What do Stephen Fry, Philip Schofield and Britney Spears have in common — aside from being famous, that is?

The answer is that they are all Twitterers. If you haven’t heard of the social networking site www.twitter.com , then be prepared. You’re going to be hearing an awful lot more about it.

Twitter is a micro-blogging service that allows people to post information about any subject that happens to exercise their minds.

Typical “tweets” can range from big news stories to what someone had for lunch. It’s one of the biggest online success stories, its number of users having grown by more than 1000% in a year.

The site has hit the headlines recently because it was the first to break the news about the plane that crash-landed in the Hudson River (one of the passengers posted a “tweet” about it, together with a picture taken on a mobile phone).

Barack Obama used it to thank all those who helped him win the presidency. And Jonathan Ross and Stephen Fry posted messages during Ross’s return to his TV chat show after his suspension by the BBC.

For some of the celebrities, it is increasingly replacing more traditional channels of releasing information. Ross used Twitter to announce that he would be hosting the BAFTA awards.

The tennis star Andy Murray shared his thoughts after being knocked out of the Australian Open tournament. And the comedian Alan Carr uses it as yet another outlet for his off-beat humour.

What makes the site different from other blogs is its speed. People can leave messages using their mobile phones. And you can reply directly to anyone, raising the possibility that you could end up in a blogged conversation with somebody famous.

But be warned: some unscrupulous users are posing as celebrities. The rising pop star Little Boots stopped using the service after discovering that journalists were using it to glean snippets of information about famous people.

So what possible use could Twitter have for businesses?

Take a look at how many are already using it, from airlines (http://twitter.com/JetBlue and http://twitter.com/SouthwestAir ) to shoe retailers (http://twitter.zappos.com ) and ice cream companies (http://twitter.com/cherrygarcia ).

Just one of those examples demonstrates what a useful marketing tool microblogging can be. The shoe firm Zappos uses it to establish contact between its staff and customers. It gives the company an aura of being human and approachable.

Dell Computers (http://twitter. com/delloutlet ) has a different approach. It has several customer service people on Twitter whose job is to find complaints about the company’s products and address them at the earliest possible opportunity. They also offer more general technical advice. See one example at http://twitter.com/LionelatDell. The site is also a platform for staff in a multinational company to converse with colleagues in other countries without running up huge phone bills.

One business owner called Richard Guerrero actually found that using Twitter was more effective and cheaper than using mail shots for his small company, which sells refurbished computers. Within a year of signing up to the site, he had sales of $500,000.

Another big advantage of the system is that it forces people to get to the point. Each “tweet” can be no longer than 140 characters, so there’s no room for waffle!

If you’re still wondering what all the fuss is about, and trying to work out how such a site could have any real value for your organisation, one businessman has kindly posted a comprehensive guide, at www.johnjantsch.com /TwitterforBusiness.pdf. An even simpler guide, on video, can be found at www.commoncraft.com/ Twitter.

If you think this is all too frivolous and not the kind of thing serious people should be doing, I have news. Gordon Brown is a Twitterer, too. Meet him at http://twitter.com/DowningStreet.

Darren Lemon is General Manager of eircom NI (www.eircomni.co.uk ). His email address is Darren.lemon@eircomni.co.uk .