Macworld has posted their review of the 2011 iMac's, and in it they have included some benchmarks of COD4 at the 21.5" iMac's native resolution of 1920x1080.
21.5" i5 2.7ghz w/ 6770m - 62.7 fps
21.5" i5 2.5ghz w/ 6750m - 52.9 fps
21.5" i3 3.2ghz w/ 5670 - 41.4 fps
The 6770m shows a healthy 50% increase over last year's 5670.
21.5" i5 2.7ghz w/ 6770m - 62.7 fps
21.5" i5 2.5ghz w/ 6750m - 52.9 fps
21.5" i3 3.2ghz w/ 5670 - 41.4 fps
The 6770m shows a healthy 50% increase over last year's 5670.