imitation is the best form of flattery. wii fans should be happy sony is going the direction of motion control.
the controller in itself is nothing innovative. the devil's in the details--like the wii mote. why did nobody make a pointing device? why did nobody do motion control earlier? it's nothing they can't do before, it's just that they all have various problems, both technically and on a design level, and putting all of them together and still have an appealing end consumer product is far from trivial.
if sony wants to bring it to the market, it's all about how the execution. even the greatest idea will fail if it's not carried out properly. for the wiimote, the sum is much, much greater than the parts.
the Wii is an epidemic.
