And here is why. the 360 adapts to software much better then PS3. So fine maybe PS3 could end up having a game at some point that is better then what the 360 can do. Problem is the 360 already has ton of games that are better then PS3 versions. With that said it is clear as a WHOLE 360 is the stronger machine. Not by brute power but by brute efficiency.
Can PS3 be more powerful yes in some small cases. Especialy with the storage advantage. We can see more options in games meaning maybe not having to use same textures as much stuff like that. But it is so far a few that no one really notices or cares.
By the time we even get close to PS3 really maybe I say maybe stretching it's legs a bit more from developers. we will be seeing the new 720. And again no one will hardly notice or care.