As for the power of the PS3 that is pure PR. Blu-Ray is a nice to have, but it has not improved gaming experience to any measurable extent. The Cell Processor isnt much more powerful than the processor in the 360 and is much harder to develop for. Multi-thread programming is perhaps the most difficult programming work to do. Make it so that different cores have different instruction sets makes it even worse. Finally when it comes to GPUs the 360 has a marginally better GPU anyway. Time and time again this generation the 360 has been proven to be the easier to develop for system. Some call this lazy but the better term is less expensive to develop for and development houses know this.
Then it comes to financials and the 360 has been profitable the last 2+ years and has years of profitability left. PS3 has yet to hit profitability. Sony is being put into a situation where they wont see profitability on the PS3 until right before the announcements of next gen consoles.
As for Wii. The only thing I have to say is that the new customer that bought a Wii will not be as easy to convince to upgrade to next gen as the traditional game system customers have been.
Its libraries that sell systems not a single game.
Essay Pro