I doubt they're banning open source per se (though that's certainly possible), but rather that the GPL ought to be incompatible with the Wii's licensing for exactly the same reason it's incompatible with Apple's App Store licensing. (Even if I'm wrong and they do ban open-source software explicitly, I still see the Wii and iPh?o(d|ne) situations as analogous from a GPL-compliance standpoint, which would still prevent ScummVM games from running on the Wii.)