Actually, the Wii is from Nintendo, so technically this is not possible. Will Nintendo be doing so? I have heard nothing, though I do not follow the gaming industry as close as I follow Apple. Apple is not even rumored to have a gaming system, though the Apple TV could be a good product for Apple to enter said market.
More and more each day it appears that Apple's gaming device is the already released iPod Touch. Very much like a portable Wii with its motion controls.