It's said the iPhone 5 screen will be almost four inches, with a resolution of 640 pixels by 1136 pixels. This is very close to a 16:9 aspect ratio. This would be the first time Apple has changed the screen size of its handset, but it might be a necessary move due to the competition.
Several leaks about the bigger screen size have confirmed each other. Note the inset picture above. The changed aspect ratio of the screen means that there is more vertical space in portrait mode than in previous iPhones. One predicted outcome is that Apple will add another row of icons to the home screen. The inset shows one more row than on current iPhones.
Probability: Very likely. Practically confirmed at this point.
(Image credit: chrisbrownie91 on YouTube.)