This gen we saw PC ports near PS2 launch, at least we saw Half Life.
Half Life on PS2 looked much worse than on over year old PC hardware, and run slower.
One could think that as things were back then, they'll be the same next gen. If Half Life 2 is ported to PS2, it'll look worse than it looks on PC today
But, as we can see, PS2 has aged quite well, much better than PS1 did. Top PS2 games are graphically (if we forget they are lower res) comparable to top PC games, witness GT4 (could well go for a top PC game today), MGS3, Jak3, R&C3.....
So, next gen PC ports will look equal in PS3. Not much better, as they share the same art, modelling and textures, physics, lighting. Equal, but not better.
But I think games specially coded for PS3 (and Revolution, xbox2)
will look beyond what top PC games can do.
Witness Teken TAG (not the jaggy japanese version), no PC game had such detailed characters, actually it took over a year before PC reached the same level (ok, comparing a figting game to first person shooters is not necessarily fair, but you can compare GT3 with PC racing games of the same era then, if you will).
Edit: Sorry, I see this topic was about that Sega's next gen game. My post is slightly off topic