You can read everything on the Visual Studio Alm Blog: Getting Started With Git in Visual Studio and TFS, but the great news is that TF Service is supporting Git as source control system for TFS Team Projects. Now that TF Service suports git, clearly we have a Visual Studio 2012 CTP addin called “visual Studio Tools for Git” that brings support for git inside Visual Studio, and it works not only with TF Service but with every git hosting like GitHub.
There are a lot of nice news, other than Git support, as an example you have a nice Tagging System in Work Items that permits basically to add whatever tag word you want to Work Items and you have a full test hub in the Team Web Access that permits you to manage testing directly from TFS Web access. Blend for Visual Studio 2012 is finally back, and Shim and Fakes features are now part of the Premium Sku and not only of the Ultimate.
So go on and download the CTP of Update 2 right now
Happy TFS and VS.