I'm loathe to say this but the pixel counting nuts at beyond3d have nailed every other game that wasn't at full rez and nail a lot of anamorphic games spot on. How the hell is this different.
The proof is in the screenshots.
Dark Sector was also 640p on the PS3 and 720p on the 360.
Why do PS3/360 owners have to always bitch and complain about everything? Can't we all just play our damn games without always bitching over which system is better?
According to reviews, XBox version is worse at pop in than the PS3 is. PS3's colours and filters looked slightly better than the XBox's extra resolution.