I've used two different approaches to teaching with blogs: the first uses one blog for the entire class in which all students are authors and tag their entries according to texts and topics; the second allows each student to keep his or her own blog related to the course. With this second version, because I was restricted by a particular blogging application that didn't allow for a blog roll, the students connected to one another by a post called "Class Blog List."
So far, the benefits as I see them to using a shared class blog are:
1. Creating a sense of class community
2. Convenience for reading and creating blog posts
3. More instructional control (i.e. you know everyone is regularly referencing the same page)
On the flip side, I've found individual blogs allow:
1. More personal freedom and sense of ownership over the material for students
2. A more "realistic" approach to blogging; i.e. one blog=one blogger
3. As a result of the sense of ownership over the site, students might have more comfort with their relationship to the writing process
I'm still in search of more ways to integrate the blogs themselves into the classroom. I've used a "blog of the day" model where I ask students to share some aspects of their post (especially for students less inclined to participate, this has been a great way to validate their voices and ideas). I've also posted YouTube videos or links to other sites as the reading assignment. We've talked as a class about the way the blog fulfills a kind of "journal" role, demystifying the writing process and allowing for more time (and space) to think through ideas from class or from the readings. However, I'm eager to hear how others have used blogs--particularly in larger classes (my classes have less than 20 students).