BuddyPress.org

I am also quite interested in the development of this plugin and can offer 20$ in support. Seems to me that this is really a standard, “gotta-be-there” feature for any kind of group system, especially (as some have already pointed out) for collaboration. So I say go for it. I’m absolutely sure it will catch on and all the more if you are using the new bp custom posts framework.

In addition to ideas already listed above, I would add the following to a wish list:
* the ability to place links to group pages in the new custom navigation system
* a solid admin system for an overview of all pages according to their group associations