No Wii version has been announced, currently available for pre-order on Xbox 360, PS3, and PC.
This is disappointing news for Wii owners, as the previous Call of Duty title, Black Ops had a Wii version on launch-date. This doesn't rule out the possibility of MW3 being released on the Wii in a later date. In fact, Call of Duty 4 was released for the Wii under the title Call of Duty: Reflex after the game had already been released for the XBox, PS3 and PC.