There will be no Modern Warfare 2 for us. In a recent interview, Infinity Ward's Robert Bowling explained that the Wii's relatively underpowered innards in comparison to the PC, PS3, and Xbox 360 make it impossible to replicate the cinematic experience  across all platforms.

Accepted Answer. They only have time to port one game per year. If they ported MW2 then we wouldn't have MW3. People would rather have the latest game rather than a game that came out 2 years ago.