Over the next few days we'll be building out the site with more information about the upcoming ShmooCon lobbying trip as well as our feature roadmap. The short version is that we'll be pulling the entire United States Code into darcs, updating it via GovTrack's APIs, and providing a UI to select and fork specific sections of the law for people to collaboratively work on.
The site's going to change quickly in the coming weeks as we add more functionality. Maybe we shouldn't have launched quite this early, but there is a bit of a time crunch.
Edit: IAC, if you're interested in more DVCS-like, offline/command-line functionality, I'm totally down to support that. Tell me more about how you'd expect to interact with that?