Curved sides are back and larger home button
If rumors from China are to be believed, some case manufacturers have apparently already gotten their hands in the physical specifications for the iPhone 5. From the shadows we hear of a return to curved sides on the iPhone 5 that are similar to the iPhone 3GS.
In addition, the iPhone 5 is said to offer a bit larger screen. The new screen is said to be about 3.7 inches and will be a more edge-to-edge screen to give it more real estate. Whispers continue to mention an improved display, as well.
The home button is apparently larger, which seems to give some credibility to the suggestion that the home button will be larger and oval shaped rather than round. This could be an indication that the area will offer some sort of multi-touch/gesture support as has be theorized for some time.
If the reported rumors said to be coming from AT&T are an indication, we should expect a mid-September launch for the fifth gen iPhone, and that does seem to match the rumblings we are hearing.