No way some of those screens are PS3/Xbox. They're probably running it on high end computers like most of us want to run it. Oh well, at least after the PS4 and Xbone come out we won't have to pray for games to come to PC. They'll be made for x86 anyway, so we'll get them all.
To be honest, I'm not impressed with the video graphic-wise. It looks like the same graphic quality (maybe an slightly optimized engine build of) as Red Dead Redemption or L.A. Noire. Not next-gen and not high-def PC. It appears to be a heavily optimized last-gen engine. Just my opinion though. I haven't been impressed with any of the screens/videos they've released as far as graphics go, so I assumed it wasn't next-gen.
I think once a PC version comes, the graphic mods will unleash the true potential of this engine.
I also said it in the news posting, I bet a "next-gen" and PC version (both being x86) come out at the same time in about 6-12 months. It'll probably turn on some of the shader/graphic features not present in the last-gen, increase resolution, and possibly draw distance.