The question of which is more powerful is a difficult one if you get down to the nitty-gritty... but I'd have to say the best snap answer is that in general, the XBox 360 actually has a narrow advantage in most ways. The PS3 has a particular advantage in a certain type of computation, but if you can't make maximal use of that for some reason, the XBox 360 wins.
The idea that the PS3 has some sort of huge advantage is mostly Sony propaganda, and people who don't get that "Cell" doesn't mean something magic that makes everything faster, it means something more like "overoptimized for a particular use case" that only makes certain very narrow tasks faster.
Now I can finally justify this point I've made before with this: There is a reason the PS4 is fleeing the Cell architecture just as fast as its metaphorical feet can take it. If companies, like politicians, weren't obligated to put on a public facade that says they never make mistakes, they would admit that it was an error and never really panned out the way they hoped (to say nothing of what they claimed!). As it is, if you read in between the lines a bit in this presentation, http://www.youtube.com/watch?v=xHXrBnipHyA , the PS4 lead came about as close as he politically could to admitting it. (Props to him. The PS4 is looking really solid to me, and I think that is essentially 100% because of this guy.)
The idea that the PS3 has some sort of huge advantage is mostly Sony propaganda, and people who don't get that "Cell" doesn't mean something magic that makes everything faster, it means something more like "overoptimized for a particular use case" that only makes certain very narrow tasks faster.
Now I can finally justify this point I've made before with this: There is a reason the PS4 is fleeing the Cell architecture just as fast as its metaphorical feet can take it. If companies, like politicians, weren't obligated to put on a public facade that says they never make mistakes, they would admit that it was an error and never really panned out the way they hoped (to say nothing of what they claimed!). As it is, if you read in between the lines a bit in this presentation, http://www.youtube.com/watch?v=xHXrBnipHyA , the PS4 lead came about as close as he politically could to admitting it. (Props to him. The PS4 is looking really solid to me, and I think that is essentially 100% because of this guy.)