“You would have to build something very console centric from the get-go,” Barnett told CVG [link broken, linked to Wired — Jack]. “I think probably the best chance of someone doing something like that is Nintendo — doing something crazy that no one expects.”
Animal Crossing Wii, anyone?
My two cents: the “crazy” part would be some kind of “easter egg hunt” functionality with a Nintendo DS. Live updates or live face-to-face interaction, kind of like that water gun game Assassin. The install base is there, anyway, and it grows every month by about 300-500k for both systems.