Nice system, Josh!
There are times when I think that trying to find that one definitive service is a waste of time, as they all do so much, but see, to miss something vital. This system is actually very close to what people do naturally, when working offline, and adds some nice, access anywhere, straight ahead collaboration as well. The low learning curve is a key factor to continued usage of any system, and this has that in spades.
Oh — and if someone happens to be looking for a task manager that does more than the silly Google Tasks tool, and syncs with Gcal too, then try Producteev. Betweein its integrations and Gmail/iGoogle widget, it will blend right into this system.