Currently there are 2 options for Git Source Control in Visual Studio (2010 and 12):
- Git Source Control Provider
- Microsoft Git Provider
I have tried both and have found 1st one to be more mature, and has more features. For instance it plays nicely with both tortoise git and git extensions, and even exposed their features.
Note: Whichever extension you use, make sure that you enable it from Tools -> Options -> Source control -> Plugin Selection
for it to work.