Thats a pretty naive statement. Just because they get the same end result doesn't mean you can sue for intellectual rights. It's like saying Daimler-Chrysler should sue all other car companies for breaching intellectual rights for copying their idea of a motor-carriage. Or the Wright brothers estate should sure plane companies for copying there idea. You can only sure for breach of intellecual rights when the device uses the same mechanism to achive the end result, and such things can be legally licensed. I'm willing to bet that Nintendo don't own the rights to the motion sensors and license them as Sony would. The only exception would be if they designed them themselves.