GamingBolt : Kojimas secret project : "NEXT"
From the way GamingBolt.com see it, this "NEXT" photo describes a new game, perhaps a new IP maybe. Though it could also mean a new Metal Gear, a "NEXT" Metal Gear, like all of us think, this could be Metal Gear Raiden, Metal Gear Solid 5, or anything else in that matter.

Though the most talked about topic is "Metal Gear Solid 4 coming to the Xbox 360", and from this photo, the chances go lower.
Like GamingBolt.com said "NEXT" means something new, a sequel, or anything like that, so if MGS4 was coming to the 360, why would he put this "NEXT" on the photo?