The deficiencies in PS3 graphics of some multiplatform games were do to the unfamiliarity with PS3 Hardware...which is all completely new, whist 360 is, years and years old (modded PC tech).
Now were seeing companies that get to know the Hardware can make absolutely ridiculously stunning looking games with 30+ FPS (Killzone 2, Uncharted, Batman: AA, Bioshock ect) which all look better on PS3.
its a mater of KNOWING the tech your designing for...360 is at its Peak, PS3 is still building. NO that comment isnt mean to build a fan war...its common knowledge to anyone who can look past their fanboy nature.
...uhh...ill just put my favorite quote of all time here.
"Welcome to Pain, the second of three...You have dealt the first...now deal with me!!"