Many thanks to George Siemens for pointing out SNAPP: Social Networks Adapting Pedagogical Practice. This is something I’ve been urging various LMS communities to build for seven or eight years (since I was involved with dotLRN). SNAPP extracts information from the discussion boards in your LMS course and provides social graphs that help you to visualize interactivity.
Example layout of discussion forum posts and replies in a learning management system, and the same discussion as a network diagram using SNAPP
It works with Blackboard, ANGEL, Desire2Learn, and Moodle (but not Sakai). The mechanism by which it works isn’t entirely clear from the project site, but it looks like you use a bookmarklet to call a web service hosted elsewhere while browsing the discussion forum you want to analyze.
There’s quite a bit that you can do with a tool like this. Here are some applications that the SNAPP site suggests: