I'm incredibly glad that Nintendo came out with the Wii - it's going to change gaming, hopefully for the better. While Sony can keep making smaller and smaller versions of the Playstation (why do you need something so small?), the Wii is changing the way people think about video games. I was at Thanksgiving and saw an entire family (not my own) engaged in a Wii Bowling tournament, from teenagers through grandparents.
Sony can keep doing what they already do, because I doubt I will ever do any serious gaming on a Playstation (I may end up with one for Guitar Hero someday) because I don't like the controller, and they can let Nintendo sell the casual gaming system.