Actually I think this is brilliant on Activision's part.
Givne that the greater majority 80%+ of gamers don't know game related news. They just see ads and game displays in stores.
How many people will go in and see a Modern Warfare game on Wii PS360 and think they are the same since they launch on same day? I'm betting a lot of people will buy it not knowing it isn't the same game. Especially since Wii titles seem to almost always be titled differently anyways.