The topic title is maybe not very clear but what I mean is this:
Your guys are having some interface that all listings backends should implement (currently git, cvs, svn)?, what if you open the interface (so say whay functions should be implemented) (I don't say that you should open the source of them immediately, although it would be cool)
Anyway if the documentation of the interface is opened, people can start on a bazaar, mercurial, whatever-vcs backend. In this way people can contribute faster, and more projects will be added. (I don't use Ohloh for several programs of mine because the bzr backend is missing).