The PS3, for a fact, copied the Wii Remote's motion sensing with their own "Sixaxis". Just a few weeks after the Wii Remote was revealed, the 'boomerang' PS3 controller was scrapped, and they showed the new one, and said it will have motion-sensing. They showed it off with a demo of a rubber duck in a bathtub. You tilt the Sixaxis and the duck would tilt. Coincidence? I think not.
And while you can argue that the PS3 didn't copy the Wii, but you can't argue that some third-party developer completely ripped off Wii Sports, to make motion-sensing sports games on the PS2. Though, these games will fail because each sport is on it's own disc, and they all have it's own Wireless motion sensing controller.
So, you'll have to spend hundreds of dollars to get all the games that were on Wii Sports, which came free with the Wii.