OpenGL ES: Turbocharged!
You will not have to throw everything you have learned so far out the window. From sprite management to touch control to the programming of sound effects, these building blocks stay the same, because OpenGL ES (= Open Graphics Library for Embedded Systems) is a pure programming interface for the development of 2D and 3D graphicsbased apps. (Advanced libraries such as GLU/GLUT are not available on the iPhone, and the audio extension OpenAL represents too much overhead for games in most cases.)
With the UIKit, we have been able to realize our ideas very quickly, but with an increasing number of sprites to represent simultaneously, sooner or later things will start to slow down. Additionally, UIKit and Core Graphics offer no support for 3D graphics. And, in any case, some of the UI animation effects of the iOS SDK were implemented internally by way of OpenGL ES.