I bought the PS3 version of Skyrim and rented the 360 version. I've played about 4 hours of each. Believe it or not I had a similar experience of feeling ill with the PS3 version. I don't know but I think it has something to do with how I'm affected by motion related to framerate. It's like I'm trying to constantly refocus or something. I had the same experience with Dragon Age: the frame lag when rotating the camera gave me a headache and made me feel sick to my stomach. My friends thought I was crazy. No issues when playing it on my 360.
Anyway, back on topic: my experience with both versions of Skyrim echos some of what others have stated:
PS3 version:
--Better textures overall
--Darker, slightly washed out colors but with good delineation between colors
--Occasional loss of framerate with some slight jitter when panning or moving
--Short freezes in the opening sequence, complete PS3 lockup on that first staircase
360 version:
--Brighter, more pronounced colors, perhaps even too oversaturated at times?
--Some blurred textures and pop-in (hopefully installing will help the pop-in?)
--Minimal screen tearing when panning although installing seems to have helped this
--Smoother, more consistent framerate overall
So in my opinion the PS3 looks better, although with muted colors, but the 360 version runs smoother with slightly less detailed textures. If it weren't for my motion issue I'd keep the PS3 version but it looks like I'm going with the 360 version this time.