For you twitter naysayers
The real money is in the businesses that can effectively advertise on twitter.
Twitter may have started out as a means for people to post inane rubbish about what they had for breakfast but recently a lot of companies, the entertainment industry, and even public authorities, have realised it's a good way to keep people informed. All you have to do is be on twitter and "follow" them. It's like RSS in that way, except the 'tweets' are more than just official press releases.
Hell, even the government is twittering now, with stuff from No.10, and I suspect some MPs too.
Twitter has already contemplated charging companies, rich people and public entities for broadcasting on twitter, but there's a problem there in that if they do that, they'll simply stop using twitter.
Anyway, don't knock twitter until you've tried it. It's more useful than you think. But if all you're going to do is add your friends or any old random crazy teen, then yeah, twitter is exactly as you predict. Used usefully and you don't even need to 'tweet' yourself, just follow people.