In case you haven't heard, a trailer for the Wii U version of Rayman Legends leaked out earlier today and showcased some of the system's unique features made possible by the tablet controller. Among them was using the touchscreen to drag platforms around and demonstrating the controller's built-in NFC technology for the first time by placing a toy directly on the controller's screen to import characters instantaneously into the game.

Both features looked very cool, but we noticed something else too, something that hasn't yet been announced...

For context, here's the back of the Wii U's tablet controller, as seen at last year's E3.

Now here it is again, but as seen in the leaked trailer:

Besides the weird, constiptated look on the guy's face, do you notice anything different about the controller? And please ignore the wire sticking out of what should be a wireless controller, which we're guessing is either being used for recharging or is part of the pre-release debug units.

No, there's something else there. Here's a closer look:

See that black-colored box on the back? That's new. But what could it be? If it's anything like the front of the controller, perhaps it houses a newly-added outward-facing camera, allowing for augmented-reality capabilities (similar to what we've seen on the 3DS). Or perhaps it contains an IR camera similar to the one inside in the Wii Remote, allowing the controller to "see" the sensor bar, thus giving it true positional awareness. Hell, maybe it's both, considering that's a pretty large area. Or perhaps it's just a sticker.

It looks pretty similar, doesn't it?

Unfortunately, the trailer doesn't offer anything else beyond this picture of what it could be. What are your ideas? Does it house a secret Wii U feature or is it nothing to get excited over? Let us know in the comments below!