I'd say that any comparison you're going to get is pretty speculative at this point. It's true that there are some PS3s in the hands of reviewers, but there aren't that many opinions available about the system and how it stacks up against the 360. If you're really on the fence about which to get, I'd wait for the PS3 to be released and read the rush of reviews that will come out then. They will, I am sure, compare the PS3 to the 360 until you don’t want to hear about it any more.
Finally, if you're interested in some (relatively) unbiased information:
Wikipedia on the PS3
Wikipedia on the 360
Wikipedia's Comparison of the "next gen" consoles (includes the wii)