9To5Mac seems to have some pretty good sources inside Apple because they have quite a lot of detail about two iPhone 5 prototypes that are currently being tested at Apple. Both devices have a 4-inch screen. And as some earlier rumors have stated, the phone will be the same width but will be slightly taller, at 3.484 inches. The new display will have the same number of pixels across, but will add 176 pixels to the height, with a resolution of 640 x 1136 compared to the current 640 x 960.
This weill change the current aspect ratio of 3/2 to 16/9 — which means that high definition videos will be able to play full screen in their native aspect ratio. 9To5Mac says that Apple is writing iOS 6 to take full advantage of the taller display and will add a fifth row of icons in addition to the icon dock. They also confirm the earlier rumors that the dock connector on the bottom of the phone will be a new smaller design.
Adding 176 pixels doesn't seem like a major change, but if you look at the mockups on the Overdrive website, which compares side-by-side how apps will look on the iPhone 5 compared to the current phone, you can see that it adds a significant amount of screen space for the apps.
9To5Mac closes with a tease, saying that have a lot of additional details coming, including processor specs, maps, and more.