Recommended Reading for iPhone Core Animation

Core Animation: Simplified Animation Techniques for Mac and iPhone Development explains it nicely.

In addition to the books suggested by Alex and nevan (of which I'd recommend Marcus Zarra and Matt Long's newer Core Animation book, given its greater quantity of iPhone coverage), I taught a class on iPhone Core Animation recently. The video for that class can found on iTunes U. My class notes, with detailed coverage of Core Animation, can be downloaded here (in VoodooPad format).

I also gave a presentation on Core Animation at the recent iPadDevCamp in Chicago, for which the slides and sample code can be found here.