When MS released Git Tools for Visual Studio 2012, they said that it requires Update 2 - http://www.hanselman.com/blog/GitSupportForVisualStudioGitTFSAndVSPutIntoContext.aspx.
I'm developing some Visual Studio extension and it's interesting for me, what they have changed in Update 2 for Extensions API, that doesn't exist in Update1\RTM.
I checked Update 2 release notes and couldn't find anything related to Extensions work. Source - http://support.microsoft.com/kb/2797912/en-us