Apparently Killzone 2 will look as impressive as the E3 demo that was shown a few month's back, according to Game Insider in the reply to an email that was sent off to the production team.

Thank you for you email. I am glad to see that you are looking into the matter at hand rather than making false judgements. The video shown at E3 was not in real time. It was a CGI demo sped up from 5 FPS as you said. The development team did this because we could not make a demo of that calibur at 30-60 FPS on the hardware we had at the time. Now however, the team is working the game on PS3 alpha kits, and it is looking just as impressive as the demo, at 30 FPS. The game is still in the very early stages of development, and I expect that it will release with visuals that are just as impressive as those in the E3 demo. We are planning on showing in game footage before too long, and we can't wait to see the public's reaction to it.

Incase you are wondering what the E3 Killzone 2 demo looks like, our old news post about Killzone 2 footage