Sixaxis is used "sparingly" in MGS4
According to this, MGS4 assistant producer Ryan Payton has said the motion-sensign capabilities of Sixaxis haven't been done to death in Konami's upcoming action game.
"The trick is to use Sixaxis sparingly and have fun with it," he said. "I don’t think anybody wants to play a long game while consistently having to tilt the controller around. Rather, it’s fun for the player when they’re given a chance to use it in short bursts– that’s how we’re approaching Sixaxis in MGS4.”
MGS4 has now been cleared for a June 12 launch in Europe and the US.