My favorite, of course, being
Mercurial. But possibly the fact that I've helped a little with it creates some bias. :-)
Mercurial Joins Software Freedom Conservancy, Retains Services of Software Freedom Law Center
Nonprofits to Support Popular Source Control Management Software The existence of a group like this at all is interesting and a generally good idea. The project founder initiated this. I'm sort of wondering how he found out about them. It's surprising to me that this is the first I've heard of them.