I had a great time last night teaching a few people about Twitter and why it's useful at the Champaign Public Library last night.
Although turnout was small, it gave us a chance to really talk about the service and what you can do with it.
If you couldn't make it, here are the handouts I distributed: my own introduction to Twitter and a blog post from Amy Gahran that I adopted about how to sign up for Twitter. 
If you ever have any questions about Twitter, feel free to e-mail me.  I love to talk about it.