Thanks to all of you who commented below to tell me why you blog with your students. The presentation went pretty well, although I could easily have used much more time than I had. A couple actually signed up for blogs during the session. In addition to some time in a technology session, I participated in a poster session where I got to talk to many teachers who weren't able to attend the technology session.
The teachers there were most impressed, I think, by your quick responses to my post. They could see the potential of blogs from that one post. I cannot thank you all enough!