I just finished listening to Miguel Guhlin's podcast with a group of teachers who are using blogs with their students. It takes about an hour but is worth listening to. One thing that really comes through is the social aspect of learning - how important it is to learn through conversation or written feedback. The students were motivated to write because they had a real audience, but they were also interested in reading what other students wrote and commenting on their writing.
Another important issue that came out of the podcast is the ongoing learning for the teachers. They, too, are reading blogs, learning from others in the field and reflecting on their own practice. This has certainly been the case for me and I thank all who are sharing.