You can't just rewrite engine code that uses 6 SPE's efficiently to run on XB360. You could need a grass-roots redesign on how to implement the different features, depending on what the SPE's are doing. IF they're just handling triangle setup etc. which Xenos can handle, a port isn't such a big deal. If they're doing something very fancy, a straight port of the code isn't an option. Then if the art assets have been optimized for a particular way of doing things on PS3, they'd need to be restructed again. Finally if the port isn't as polished as the original, as often happens with ports, SE might be unwilling to release a lower quality product, especially of their flagship title. If the XB360 isn't of the same quality as the PS3 version, a release likely wouldn't happen. And without knowing the ins and outs of the White Engine and it's implementation, we can't safely say a port of the engine is cheap and effective. Obviously SE have decided the cost to port isn't worth the returns. Either the costs are low but they rate the market as negligable, or the costs are significant and they don't feel the XB360 market viable to cover those costs. I think the latter is perhaps more accurate, especially seeing as SE have bought in UE3.
[or UT3]
