Moto X: Mysterious Sensor

I'm wondering why the upper right corner of every leaked image of the supposed to be Moto X is always covered or seems photoshoped?

Pjhju_medium

via www.freeimagehosting.net


Yrfyk_medium

via www.freeimagehosting.net

"At D11, Motorola CEO Dennis Woodside[...]has said that "we know when it's in your pocket, we know when it's in your hand, it's going to know when you want to take a picture and fire up the cameras." It'll know when you're in the car, for instance, and promote different interactions."

So you need a loot of sensors for that. But Cameras for 3d awareness are already in the place:

Fy963_medium

via www.freeimagehosting.net

It has to be a special sensor, but what kind of mysterious sensor could this be?