Btw, if you haven't heard about this game yet, it's from the developer of the Sims games. You really have to watch through the whole game demo in order to get a sense of just how HUGE this concept is. It's like a dozen meta-genres rolled into one game.
The inclusive use of 'Procedural Content' is the really the most amazing aspect of the game. I'm still a little unclear how the 'asynchronous multiplayer interaction' plays out...my impression is that you play as a single player, build your own world, define the constraints of the characters inhabiting it, as well as the build the environment, then someone can visit that world and it's added to their game (via download). From there, do they evolve it, or is the content 'pulled' and updated from your world?
mrC