In an interview with Famitsu, Hideo Kojima, creator of the Metal Gear Solid series says that MSG4 is exclusively for PlayStation 3. He prefers to crate original titles for all consoles (Xbox360/Wii) instead of porting them. His words about the 3 consoles:

“As a developer, I see the three consoles as different kinds of meals,” said Kojima. “The PlayStation 3 is a sumptuous feast for special occasions; the Xbox 360 is a fine Sunday dinner; and the Revolution is a rich, home-cooked supper.”

Now we only have to taste the 2 remaining meals to find out if it was worth it.

Via CNet.com