I have been running a tutor blog for my ESP students studying Image & Sound. I introduced them to blogging in October, and they have set up learner blogs (see links on the tutor blog) and have used their blogs as a way of submitting assignments that can be then read by others.
I have been looking at ways of presenting corrections to students, writing comments to their weblogs, and have told them to feel free to use the weblogs as much as they like. A large proportion of these students don't have access, or have limited access to the Internet from home, so they have not been using the blogs much. Still, it's been an interesting experiment and most of the students seem to be happy using blogs.