I'm very pleased with github as a code hosting site, and I like the way they allow you to publish a static site, and the wiki feature is useful... but I'm not sure the wiki is so usable for a larger group of contributors. Although the wiki is under git control and so does allow any to roll back changes, you can't so easily see and revert changes on the web view. I'm not sure github allows easily for a distinction between contributors and moderators.
I've been looking for an ideal discussion forum platform(*), and haven't yet found one, but today I did come across two which look promising:
(One of the features I'd demand would be full export of the group data in some structured form, so the group can be relocated to a different provider if need be. Perhaps with some effort, but at least possible. I don't know if the above two offer such an export.)
(*) My ideal may not be your ideal, of course.
feedback, comments and suggestions pertaining to the *. forums