VG Resource Center
"Yes, in fact, we are working on putting Metal Gear Solid 4 on the Xbox 360 and PC, which should both come out roughly 6 months after the PS3 release. However, we've been working with Microsoft so the 360 and PC versions will both take advantage of Xbox Live and Games for Windows Live, with such features as achievements and the ability for 360 and PC owners to play against each other in multiplayer.
I'd love to give you some more details, but this is already pushing it. We are making the big announcement July 11th at this year's E3, so you'll just have to wait until then. Sorry!"
- Donald "dpcough" -