Nintendo Enthusiast appears to have gotten ahold of a photo showing a portion of Nintendo's E3 booth either in the midst of being put together or arranged for transportation. I'm sure this is every E3 presenters nightmare, but the photo does seem to reveal a currently unannounced game for what I believe to be the Wii U. The game's name is Mario Maker, and judging from the sign it seems to be a game revolving around build classic Super Mario Bros. levels.
That's entirely just speculation on my part, however. Not to mention that until officially confirmed this is all rumor anyway. E3 booth sets are typically under extremely high security. Yet when all there's really to go on is a blurry photo of a sign not really intended to give much information about a game, then by god we'll do as much as we can with it.
In the image the Wii U stylus appears to be dragging either an object or an enemy for placement on the level, implying a level of control in designing the level. The other notable thing about the level is that it's filled with various junk including pipes, platforms, wall blocks and enemies. The two put toegether make it seem like the player is constructing the level, placing obstacles as they please.
The question then becomes what the point of the level design is. Can the player then play through the level they've created? Is there something more complicated to it, like an AI simulated Mario that then has to traverse the level? Is there an assymetric multiplayer to it that challenges players to go through player-made and shared levels? There are many directions a Mario Maker game could take.
Expect more information on Mario Maker, if it proves to be real, during Nintendo's E3 press conference on Tuesday, June 10, at 9:00 AM PDT.