G-G-G-G Gitoorious!

Gitorious is an open source Git server! Allows you to host your own Git repository :) http://www.gitorious.org

Side note: check this plugin out:

Git p4 allows the cloning of a perforce repository into a git one and back.
For documentation:

Perforce: http://kb.perforce.com/article/1417/git-p4
MIT: http://stuff.mit.edu/afs/sipb.mit.edu/user/tytso/git/git-
Git wiki: https://git.wiki.kernel.org/index.php/GitP4
Git docs: http://git-scm.com/docs/git-p4

There is also a perforce product called git fusion which seems cool for enterprise: http://www.perforce.com/git-fusion