While some reports had called for a uni-body casing for the Apple iPhone, the model being produced will include an inlaid piece of glass between the top and bottom edges. That will replace the original design of a plain aluminum surface on the back of the handset. The current Apple iPhone 4S and the Apple iPhone 4 are both like a sandwich with Gorilla Glass covering the front and back of the models. The new design has a backplate that will be only partially covered by the glass material. Speculation has the change being made due to an increase in the display size to 4 inches and a change in the aspect ratio to 16:9.
The microphone hole between the camera in an earlier picture (top) is not seen in the newest photo of what is alleged to be the next Apple iPhone chassis
The sixth generation Apple iPhone is expected to launch in late September or early October. There is thought that Apple wants to release the phone as early in September as it can in order to have the phone ship during Apple's fiscal fourth quarter which ends in September. Last year's launch of the Apple iPhone 4S in October forced the Cupertino based firm to account for the launch of the phone in the first fiscal quarter of the current fiscal year. This led to an unexpected shortfall in earnings for the fiscal third quarter which momentarily stunned Apple's stockholders.
source:Macotakara (translated) via AppleInsider