The digital foundry face-off is finally up. Basically we have platform parity. There's only a slight framerate advantage on the PS3 and the usual 7.1LPCM, 5.1LPCM, DTS audio options that aren't available on the 360.
What you might want to consider if you own both consoles is this:
"In terms of the impact on the gameplay experience, the two-disc setup is a touch intrusive but nothing that is going to overtly affect your enjoyment of Lords of Shadow. The game has 12 chapters in all - five on disc one, seven on disc two - and the change-over point is seamless enough; you swap discs and the game doesn't bother you again. However, part of the game's charm is that the powers you unlock in later sections of the game allow you to access areas of earlier levels, adding a lot to the replay factor. You can even go back whenever you want and continue the main quest at a later date.
Now you might think that having both discs installed to HDD would allow for no swapping at all, but that wasn't the case when we reached chapter six, and it wasn't the case when we immediately went back to the previous level. In both cases the disc needed to be inserted even though we had all the data immediately to hand on the HDD."
Anyway, the framerate is a bit disappointing as we suspected after playing the demo but it's also one of the best looking games on the market.