Team Foundation Service by Microsoft
tfs.visualstudio.comWhile upgrading to Visual Studio 2013 you're prompted to create your account on the new Team Foundation Service site.
Overall feels pretty interesting. One thing of particular interesting is "cloud based load testing" service available for hosted repositories.
http://tfs.visualstudio.com/en-us/learn/load-testing
I'm a huge fan of Github and I don't see myself changing anytime soon, but I'm interested to see what features end up a part of the TFS offering.