jwz explains why there isn't any usable open source groupware, and why it's a bad idea in any case:
With a groupware product, nobody would ever work on it unless they were getting paid to, because it's just fundamentally not interesting to individuals.
So I said, narrow the focus. Your "use case" should be, there's a 22 year old college student living in the dorms. How will this software get him laid?
That got me a look like I had just sprouted a third head, but bear with me, because I think that it's not only crude but insightful. "How will this software get my users laid" should be on the minds of anyone writing social software (and these days, almost all software is social software).
