In an interview with Official PlayStation Magazine, Hideo Kojima said, "The controls in MGS3 got a little complex, so you'll have a little more direct control in MGS4. That said, I miss the rumble and even now I hope it will come back."
Don't hold you breath as Sony got stung badly with the rumble technology it used in the past. As far as how MGS4 will use the motion-sensing technology, Kojima added, "We can't say how we'll use the motion-sensing functionality specifically but we'll use it for sure." Do you think he means they don't know yet?