ORIGINAL: Yankee
Well right now it's assumed that the Camaro will have the 400 hp 6.0 LS2, but now that the Vette has upgraded to the 430 hp 6.2 LS3, I'd bet that the Camaro will have a version of that as well, which would put it about on an even plane with the 425 hp 6.1 SRT motor. Even with the LS2, though, I'd probably (as much as it pains me to say this) give the Camaro a slight edge, largely because the Challenger is such a porker at 4100+ pounds.
Of course if Chrysler decides to up the hp on the 6.1 by next year (or 09), then my take might be different.
I have serious doubts that the Camaro will have the same engine as the base level Vette. As Patrick has said in the past, the last Camaro was threatening the sales of the Vette by offering the exact same engine as it and selling it for a lower price, and they even doctored the engine output numbers to prevent that from happening and it failed to trick anyone. Think about it, what other reason would the up the engine in the Corvette? Since the G8 will feature the 6.0L (granted a lower output version) I would expect the Camaro to share the offering. Economies of scale.
Right now, I'm not speculating on anything. Too many factors are still unknown on both models.