Well, I picked it up this afternoon and I can say that yes, it DOES have 3D splitscreen. As far as I know, GT5 may be the only PS3 game with such a feature as of yet. My whole family sat around and watched. I like that you can tweak the 3D effect, but it would help to have an image preview.

I haven't even started single player yet, but this is really impressive so far. I've never played GT, or very many racing games at all for that matter, so my opinion might be different from that of a longtime fan. It's really fun so far, but I wish that I had analog throttle.