i have created a simple addon for basic git versioning support.
That means you can commit and checkout blend versions from within blender.
You also can view a brief history of the current blend.
Furthermore basic branching support is there, but it probably is not much useful
because diffing and merging of binary files is not compareable to diffing text files.
(What to do if there is a conflict ? )
You can find the addon zip in the blender addon tracker: