I have. I signed up, I followed a number of "interesting" people, including many tech people, and a bunch of friends followed me. I used it as advertised for several weeks. I don't like it. I just haven't found it interesting, and I don't care about broadcasting what I'm doing to people who don't know me. I guess I feel it's a tiny bit narcissistic to think that people I don't know care what I'm up to every minute.

I also have a bias against Twitter. Apparently I have the same name as some Canadian Christian Rocker, and I get a ton of people following me because they think I'm him. Every once and a while I send out a message saying that I'm not him, but because of that wonderful stream that everyone touts, I'm sure they never see it.