This was console lead on PS3. Irrational Games stated by getting the code to run well across multiple processors on PS3 would mean a more efficient code on the 360 and PC as well.
http://blog.us.playstation.com/2010/08/12/irrational-games-next-project-coming-to-ps3-first-video-and-ken-levine-qa/
http://blog.eu.playstation.com/2011/08/09/bioshock-infinite-qa-ken-levines-playstation-moves/
The differences are minor though with 360 having a lot less screen tear and higher res shadows but with a framerate penalty while PS3 get's faster texture streaming, better texture filtering, better frame rate but at the cost of more screen tear due to a more liberal use of adaptive v-sync.