So if I understand it correctly the client-to-server API is simple but servers internally build a Git-like structure? Interesting design, I think I'll read the specs for how history is stored.
Seems we now just have to wait for the next generation that's a rip-off of piul[1] rather than git, and we'll be all set!
On a more serious note, this seems to be a trend; to model chat as a converging set of edits. From an architectural pov it sounds similar to Google wave and lotus notes.