My only shock here is that this wasn't done sooner.<p>I have kind of seen Git as two tightly coupled systems (and IIRC, other VCS's have modeled their design with a similar separation of concerns): a content addressable store, and a tagging/tracking system for metadata.<p>I actually kind of expected that someone would eventually try out replacing one of the two with their own "better" system to see how that worked out, but obviously the more interesting opportunity is to see if one or both of the components might be useful for an entirely different purpose.