Somewhat off topic, but I'd love to see something more git-like that works for large repositories. I work on video games and our repos are several TB. It's not practical to use git in those situations and Perforce feels too clunky to me.
I'm looking for something more like CVS/Perforce where you can check anything in, but then with a more Git feeling interface. What I'd really like to do is to look at Git feature by feature and build the closest thing possible that does not include cloning the entire history locally under normal use. I know that is the fundamental paradigm of Git, but it seems that something closer to a hybrid of Git and Perforce could be created. Not sure exactly what it would look like. It's just jarring to jump from Perforce/CVS to Git and I don't think that's completely due to the local repository model. It's how branching works, it's how merging works, etc.
I would put all binary files into git annex (as determined by `file`). This can be done by a commit hook automatically. With another hook that makes sure that `git annex pull` is run when the user checks out code, you'd have a solution that was close enough to automatic for most use cases.
(You'd have to help your users with weird situations from time to time, but that's true of git anyway.)
tl;dr: all the data sits in one or more binary server[s] and is fetched on demand when you ask for the file. We distinguish between text and binary so you can clone a tree and have all the text checked out and none of the binaries; you set up your build system to check those out as needed.