Exactly, there are a few MSDN/Channel 9 articles describing the pains of pulling the Windows repo into Git. If anything, Microsoft is going to make Github, and Git, much better. They have the largest code bases in the world, they aren't going to change anything that will disrupt internal processes, but will build tools to help others with massive codebases live better in Github.

I also don't see it - but isn't making Git 'much better' essentially extending it? If they released some kind of tight integration that was actually really useful and only worked well in the github context, don't you think people would use it? I can't imagine what form such a thing would take, but it definitely seems possible.