The biggest hurdle that the PS3 will have to overcome.

[MikeB]

@ Diomedes1976

Currently ,the ports of X360 games in the PS3 only use the PPE and the RSX

I think you are right, just look at the wonderful graphics together with good performance Genji 2 delivers, that game is confirmed not to be using the SPEs at all. So even without tapping into this huge  fllexible  (graphics, physics) performance potential games can look amazing, on par with the best graphics we have seen in XBox 360 games so far. But other than graphics IMO Genji 2 isn't that impressive regarding for instance physics and AI and general gameplay.