We’re building something along these lines at Axon (http://axon.science). Sign up for our beta if you’re interested in checking it out, and we should be able to get you set up in the next few days (we’re just starting to roll things out to the public this week).

The basic idea is distributed version control, like git, but over p2p swarms rather than clusters around “central” repositories. We have special handling for large datasets (but still using git) to improve transfer efficiency and diffing.

There’s a UI layer for collaboration (discussion, PRs, review) that supports deep linking to and embedding of files at specific commits, which sounds a bit like what you’re looking for.

Feedback is very much appreciated!