It looks like gamespot and IGN have ranked the ps3 version lower. Gamespot gave the ps3 an 8.5 vs a 9.0 for the 360. Additionally, IGN gave the ps3 version 9.4 while the 360 got a 9.6. From gamespot:
It's a shame, in light of these impressive design elements, that the PlayStation 3 version is shockingly inferior to the others from a technical perspective. Although the Xbox 360 and PC versions display the occasional visual oddity and bland texture, these nitpicks are easy to overlook. Sadly, the jagged edges, washed-out lighting, and slightly diminished draw distance of the PS3 release aren't so easy to dismiss. We also experienced a number of visual bugs on the PS3. Character faces disappeared several times, leaving only eyeballs and hair; limbs on robots went missing; some character models had an odd outline around them as if they were cel-shaded; and the day-to-night transition may cause odd streaks on the screen as you move the camera around. This version doesn't even offer trophies, whereas the Xbox 360 and PC versions offer Xbox Live/Windows Live achievements.
http://www.gamespot.com/ps3/rpg/fallout3/review.html?page=2
