Almost all the multiplatform games I've seen look better on the 360 than the PS3. The PS3 is powerful but the Cell processor is so hard to work with that companies don't spend as much time developing for it and tweaking it for the console. In the game development world, time is money.
I agree. Some of the PS3's better titles like Resistance and Lair looked horrible. If you compare the graphics of Gears of War and Resistance: Fall of Man, I'd take Gears hands down. Resistance totally reminds me of FEAR and it's repetitive, linear levels with the same bland look everywhere.