In my company we are building a Drupal distribution for this purpose, called GroupMind, with some interesting features:
- Gamification (badges and points)
- Project sharing
- and many more
If you want to have a look at it:
- GroupMind project on Drupal.org
- Bonitasoft Community (production)
Please, let me know what do you think of it. It is still a work in progress, and we are looking for feedback and contributors.