And, you'll be increasingly coming across Mercurial, since it's been adopted by Mozilla four years ago, by Google in 2009, and is preferred by Windows, Python, and Django developers. (89% of our respondents have heard of GitHub and 62% of its Mercurial sibling BitBucket.)
"Adopted by Google" here seems a bit disingenuous; they offer Mercurial as an option for developers that want to host their OSS projects with Google, it isn't as if Google's in-house source control has moved to Mercurial.