If Sony can make their motion controls work as well as the Wii + WiiMotion Plus, and developers can provide games to take advantage of them, then that will be fantastic.
I bought a Wii about a month after I got my PS3. I've had the Wii now for about a month, and the PS3 for two. My PS3 hasn't been powered on in over a week except to play a DVD.
All of my gaming time of late has been spent playing WiiSports Tennis, and now, as of yesterday, VirtuaTennis 2009. Tonight, I pick up two WiiMotion Plus controllers, and Grand Slam Tennis. I hope to pick up the new Tiger Woods Golf soon too. I have its demo on the PS3 and it's very good; I can imagine it being even better with the Wii's controls.
Still, I figure once I start to tire of the tennis games, I'll go back and continue playing Uncharted, Fallout 3, and Wolverine. I still LOVE the PS3; it's a technical marvel and I love technology. I'm eager to see what happens with Sony's new motion controls. I would LOVE to see the Wii's controls coupled with the PS3's horsepower and amazing graphics.