Taken from Joystiq:
Don’t be fooled: this is not a sign that Bethesda is bringing its Elder Scroll series to Nintendo consoles. However, Emergent Technologies’ Gamebryo engine — which runs both Oblivion and the upcoming Fallout 3 — now supports the Wii.
Gamebryo is also optimized for PlayStation 3, PC and Xbox 360. We haven’t seen any screenshots of the engine in use with Nintendo’s hardware and no projects have been announced; the Gamebryo engine has also been used to make Freedom Force, Civilization IV and Dark Age of Camelot. Will we start seeing a significant visual improvement in Wii games? That’s entirely up to the game makers, to be honest.
For now Fallout 3 is being made for the PC, XBox360 and PS3, but who knows about the future, if Bethsoft one day decides to make a Fallout game for the Wii their work just got easier.