The new iPhone 5 display has a new aspect ratio and a new resolution (640 x 1136 pixels).
What is required to develop new or transition already existing applications
Peter, you should really take a look at Canappi, it does all that for you, all you have to do is specify the layout as such:
button mySubmitButton 'Sumbit' (100,100,100,30 + 0,88,0,0) { ... }
From there Canappi will generate the correct objective-c code that detects the device the app is running on and will use:
(100,100,100,30) for iPhone4
(100,**188**,100,30) for iPhone 5
Canappi works like Interface Builder and Story Board combined, except that it is in a textual form. If you already have XIB files, you can convert them so you don't have to recreate the entire UI from scratch.