PCGH has used the command console of Crysis to play the game at 6,400 x 4,000 pixels. This is possible on a 30 inch display because the Cryengine seems to downsample the game to the native resolution of the screen (2,560 x 1,600). Therefore the picture you see has 6.25x SuperSampling Anti Ailiasing. They have taken some impressive screenshots.
If you are registered at the website (free) you can download four of the shots at 6,400 x 4,000.
This isn't a huge deal... I've got a whole folder of screenshots taken at 19200 x 10800.
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You know this site makes me laugh, if this had been Killzone 2 at 6,400 x 4,000 there would be at least 200 comments by now going "wooo power of da cell baby". However because it's the PC doing it, we get "meh what's the point".
about 3 fps.