I just read on Inside Higher Ed about an experimental social learning component that Stanford is adding to one of their most popular iTunes U courses (iPad and iPhone Application Development).

They are using the platform Piazza, which Megha reviewed on the EdLab blog last summer, to enable students to interact and learn from each other. At this point, it's just a pilot program for the summer to see how it works for such a big community of learners, so we'll see what kind of implications it has for social learning and the architecture of Piazza's system in a few months. I am not sure if I would want to be one of the teaching assistants moderating the discussion boards for this class.