Even Hideo Kojima himself the owner and creator of MGS series said: "no way in hell would MGS 4 ever appear on XBox 360". Kojima is a big fan of PS3 and he hates XBox 360.
Keep dreaming 360 fans and enjoy the games you have and tell your company stop stealing PS3 exclusive games. It is not fair. 360 stole DMC 4, GTA IV, FF XIII at E3 08' and now Tekken 6 at TGS 08'.