According to many highly credible sources who have already gotten their hands on both PS3 and Xbox 360 versions of Call of Duty 4, the news is that they are nearly identical.
Many gamers were worried that Call of Duty 4 would not run as well on the PS3 as on the Xbox 360. A lot of this was due to fears learned from the past with EA Sports games having framerate problems, games such as Madden NFL 2008.
PS3 owners have no fear though as yesterday PCN was able to confirm that Call of Duty 4 will run on 1080p on the PS3.