Metal Gear Solid 2 was released on the Xbox >.>...
And I agree with Mammy, mostly because I hope he's right
. Anyway, Kojima doesn't decide whether or not the game gets ported to 360 (he had nothing to do with the MGS2 porting to Xbox) and even then it wouldn't be a bad decision on Konami's part to port the game, for a whole lot more profit. The simple fact is, if people like Mammy aren't buying PS3s to play Metal Gear, a lot of other people aren't either. And hey, profit is profit.
Of course, there's a lot of reasons why MGS4 wouldn't get to 360 as well. Mostly related to "promised exclusivity" (pfft) and Sony paying Konami not to.