I think I understand the appeal of Twitter now. It is all about lower time commitment. If you really want to it is not that hard to say what you want in 140 characters (and you get the extra benefit of being able to filter what other people are saying fast). On top of that, the fact that you can tweet @ someone is a stroke of genius. It is the perfect mix of IM, email and blog.
Now I see why so many people who stopped blogging still tweet. I will still do both because I have so much verbose rants inside me but the share of my time here is smaller now.