Apple has been testing the taller display setting, unnamed sources told the blog. 9to5Mac used iOS development tools to simulate a 640x1,136-pixel resolution screen, which gave the phone five rows of icons stacked vertically above the dock, instead of the four displayed with the current iOS.
The simulator would not correctly display the five rows at any resolution other than 640x1,136 -- other resolutions scaled the icons to the size used for iPads, according to the blog. View the screenshots here.
Rumors surfaced in May that Apple plans to launch a phone with a 4-inch screen, no doubt exciting iPhone users who would love to see a bigger screen, particularly as other phone makers increase screen sizes.