The SSG has been hearing good things about Bitbucket.org's Academic License. It is being used in the CS in labs and for instruction. The unlimited license provides unlimited repositories, unlimited users, and 1GB of space per repository*.
Bitbucket's site covers both Git and Mercurial repositories, with wiki, issue tracking and pull requests.
*Repository size limits are:
Soft limit of 1 GB – In-product and email notifications will give you a heads-up that you’re approaching the limit.
Hard limit of 2 GB – Pushing to the repository will be disabled until you’re back under the limit.
The prefered revision control system of the SSG.