It's been known for quite some time that Wii focuses on gameplay/controls, not graphics. Again, it's going to be more powerful than the original Xbox and it's actually been said (sorry, I don't have the source) Wii will be twice as powerful as the Gamecube.
And no, Sony can't just duplicate the Wiimote/nunchuk; they'd get sued. The PS3 only has tilt sensetivity, so it doesn't know how far away from the TV it is. This means it can't tell when you're making jabbing motions like you can with the Wiimote, which in some games translates to actually stabbing with a sword. Oh, and the PS3 controller doesn't even have rumble. The PS3 controller's tilt sensing feature will probably be used only for driving and flying games and to me, it just seems like a gimmick.