I tried to bring it up before, but anyways: drupal looks like a good way too go. It's fast, foss, flexible and with these modules
I did some looking into this myself. Drupal looked interesting, but the solution that seemed simplest and best to me was using a phpbb and a mailman <--> phpbb gateway. So we're experimenting with that at the moment (thanks, Newman :-/).
The plan is to continue fuddling and let some data fill, and then cut it live in a day or so. If we hate it, we can continue looking for a solution...
Cheers,
Jeremy