Ever since we started to hear about the iPhone 5, one of the first rumors was about the screen size. Since then, numerous leaks and speculation have led us to believe that the iPhone 5 will have a larger screen set at 4 inches. Apple won’t say one way or the other until they formally announce the device in September, but the current beta for iOS 6 might have already spoiled the surprise.

Developers who already playing around with the latest release of the iOS 6 beta have found something interesting. The current iPhone screen can only display up to four rows of apps on the home screen. iOS 6 beta 4 is able to scale the screen to a new resolution of 640×1136 and display five rows on the home screen.

Here’s a comparison of the two screen resolutions courtesy of 9to5Mac:

The increased resolution and app rows pretty much confirm that the iPhone 5 is going to have a larger screen. It makes no sense to include an option for scaling if the screen wasn’t going to get an upgrade. Here’s how 9to5Mac was able to increase the resolution on their current iPhones:

Thanks to some tweaks to the iOS Simulator application that is included in the iOS development tools, we were able to run the simulator at the rumored next-generation iPhone display resolution of 640 x 1136. We did this running both the current public release of iOS 5.1 and the upcoming iOS 6.0 The iOS 5.1 simulator displayed the home screen with a stretched set of four rows of icons. On the other hand, iOS 6 displayed five complete rows – as our sources said Apple was testing for taller iPhone displays.

It’s important to note that this just a simulator. It could just be a testing bed for new features, and hardware, down the line. Considering that the longer screen has been in just about every leak, however, there’s a good chance that we’ll see a larger iPhone in September.