The LMS Group is looking at Sakai as one of the possibilities to replace WebCT. Sakai is a community-source project, originally intended as a replacement for Lotus Notes though now being used extensively as a learning management system.
If Sakai is chosen as our new LMS - an even if it isn't - I think it's worth a close look as a possible collaboration tool. It also has some communication functions we should look at.
This video gives a good overview of the Sakai Project.