I have yet to find "normal" people exchanging non-worthless information on Twitter.
As near as I can tell, the situation can be summed up thusly: People that publish or broadcast are rightly smitten with Twitter since it fits well with the model of one-to-many information exchange.
What that results in, however, is an inaccurate representation of the usefulness of it by the media. I get to hear all day from bloggers and broadcasters how miraculous Twitter is (and for them it is), yet every time I attempt to avail myself of it I'm utterly disappointed with the signal to noise ratio.
At best, Twitter is a mechanism for press releases with a 140 character limit. At worst, it's a stuck open valve from which people dribble their mental diarrhea.