The PS3 is in part, a vehicle for Sony to push BlueRay. BlueRay is why the PS3 is delayed, BlueRay is why they are shipping in such small numbers, BlueRay is the new BetaMax. The PS3 is aimed squarely at the developing HD market, has sumptuous cinematic graphics and is intended as the HD media hub for your living room. XBox 360 is targeting the same market but is backing HD-DVD.
The Wii doesn't even supoort DVD playback. The Wii gaming experience is about fun and interaction. Playing Wii Sports is fun, playing it with friends is a blast. The PS3 looks to have absolutely stunning graphics but I think they've lost sight of the fun part as they go after the digital hub market.