I've had a Twitter account for 223 days now. I do follow several friends and coworkers with Twitter. What I find more interesting, however, are the people I don't know or have ever met whom I follow.
Officer Phil is a good example. (Bonus: He's a fan of Norm MacDonald.)
The use of Twitter over the past SxSW crippled the SMS feeds, also slowing texting. Twitter is everywhere and I am very concerned about Twitter abuse. Tread carefully.