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 to the new screen size?
What should we keep in mind to make applications "universal" for both the older displays and the new widescreen aspect ratio?
[[UIScreen mainScreen] bounds]as there seems to be no specific API for that. As of iOS 8 there are also size classes that abstract screen sizes into regular or compact vertically and horizontally and are recommended way to adapt your UI.