The 360 looks the same or sharper to me. I'd give the following games the advantage to the 360:
Fallout 3
Dead Space (how can you ignore those lines on his back? that's horrible.)
The Force Unleashed
Mortal Kombat vs. DC
That being said, if you're actually playing the game I doubt you'd even notice the differences. It is kind of sad that a 400 dollar system can't beat a 200 dollar system in terms of graphics. Depending on your needs I understand the PS3 can be a better value, but yeeesh...