[quote=apple]Starting May 1, new apps and app updates submitted to the App Store must be built for iOS devices with Retina display and iPhone apps must also support the 4-inch display on iPhone 5. Learn about preparing your apps by reviewing the iOS Human Interface Guidelines.[/quote]
Not sure how many of us that effects but does mean you need to make sure you apps are responsive to fit the different aspect ratios and have minimum size of 640x960. Don't think letter box scale will pass as it just renders a black bar.