I can't see how this would be a bad idea.
Git is great for managing large and small amounts of information. Binary or text are both allowed and kept revision history of.
This could probably work just like iFolder, but with much better ability to merge, keep history and share your information.
One of the problems is the complexity unerlying this kind of setup. Unless your users are well versed in git branching, conflict resolution by merging, and applying patches manually, you will have to make some tough decisions on how to dumb down the system.
The idea of GUID is also going to be confusing to end users, so you might have to build something simple (version numbering) on top of that.
The no-empty-folders allowed dilemma is also one you will have to address.
The good thing about git (as opposed to svn or iFolder) is that moving a file is easy, and merges are smart.
Overall, git does good managing our binary image, media and code files all in one repository. I can't think of why it could not be used as a helper for any other kind of project, to keep track of documents, images and other media.