A new trailer released just recently with the Xbox One launch has teased exclusive Metal Gear Solid V: Ground Zeroes content.
The video doesn't get any more specific than "exclusive Xbox content," however, so we have no idea if it's actual gameplay or something as minor as a skin. Also unclear at this point is whether the content is for Xbox One, Xbox 360, or both.
The PlayStation exclusive for Ground Zeroes wound up being a "Deja Vu Mission" that lets players access a Solid Snake skin based on this 1998 appearance in Metal Gear Solid. Maybe the Xbox exclusive content will be similar -- Raiden skin, perhaps? I'd rather have Snake, really.
Metal Gear Solid 5: Ground Zeroes is expected to come out in Spring 2014 for Xbox One, Xbox 360, PS3, and PS4.