Macitynet posted a photo of the unit yesterday noting that case manufacturers use these models to test the fit of their new case designs.
The iPhone 6 will have rounded edges and the Standby button will be shifted to the right in order to ensure easy access when used with a single hand, given the increase of the display which will expand slightly on the short side of the device. We see however also two thin lines on the upper and lower edges that probably indicate a design similar to that of the iPhone, characterized by an aluminum back but broken by two bands in another material (maybe in the glass as the iPhone 5S) which should ensure proper operation of the antenna. Of note, the projection lens of the camera; the technical solution is the same as for the latest generation of iPod touch, remember, has just a protruding ring that protects the glass lens, reading to the surface of the back.
Most of the leaks of late have pointed to this new rounded design; however, none of the leaks have been confirmed and case manufacturers have been wrong in the past.
Check out the other physical mockup here.