To put it into perspective, I originally played Crysis on a single core A64 @ 2.4Gghz with 1GB RAM, and an X800 card. I had everything at minimum settings @ 800x600. Guess what? It was still the most amazing looking game I'd ever seen and it looked better than any game graphically on either console (except for COD4).
The PS3 has something similar to a 7900GTX inside it, as well as a processor that will kick the shit out of a single core athlon. The only concern is one of RAM. The PS3 has 256mb XDR system RAM and 256mb gDDR3 RAM (I believe) of video RAM. That will be the struggle. However, after playing through Crysis and FarCry, doubting the capabilities of Crytek would be extremely silly and naive. Unless of course they dump the port onto some other developer, in which case we can only hope for a decent (not amazing) game.