Right. The current annotation UI, co-ment, does all of its versioning in a database. Distributed version control provides certain advantages over this, ones that we'd like to bring in quickly, but it's vital that we convey our goals to both non-technical and technical audiences.
We're actually partial to darcs for this particular use case (the patch model is closer to how laws are actually amended), which ironically may decrease traction on the command-line since everyone has such a hard-on for git these days. IIRC you can use darcs via git, though.