PS3 has the edge because it has much of the technology as the Kinect due to the Playstation Eye camera, but it also has a physical controller which is pretty much necessary if you are going to be playing any hardcore games with motion controls.
what a bunch of uninformed crap.
If you have a nice TV and don't have a Blu-ray player, then the PS3 is very tempting. That having been said, and an owner of both, the PS3 I don't game with. It is only used for movies. I have some good games for it, but most of the cross platform games just feel better on the 360.
So if the primary purpose is gaming, you are probably best off with the Xbox. A decent Blu-ray player is only a $100 these days - the price difference of an Xbox and PS3.
As for motion gaming. Kinect is a hit, and as a result is going to get a lot of games developed for it. Right now there are only a few decent games and they are 100% kinect, but MS promises games that use the Kinect in addition to a controller - Think FPS where you give out hand signals to teammates, or lean around corners. Kinect is the only one that can track full body motion. It is the only one where the initial cost is the whole cost. It is the only one that can (not in current games, but demonstrated in tech demos) do finger tracking.
The Move has casual games but is also trying to appeal to the hardcore gamer from launch. They worked the Move into some FPS games as the main controller. It was really gay looking. Since the Move sales have been unimpressive, expect less Move only games, and mostly games that can use the Move in place of the regular controller.
No need to get a wii now that all platforms have motion gameplay.
I may be biased because I bought a Kinect (on its way as we speak), but frankly I could have bought any of the three, and the Kinect was the only one that impressed me.