here is a freebie: an iBook from Stanford University about iOS programming

If you want to start programming for iOS and you are looking for a great starting point, please download this free iBook from the iBookstore: CS193P: iPad and iPhone App Development. This is one of the best iBook experience I found on the iPad. Really nicely done.

Building "My iOS Dev Bible" with iBooks Author

I've been ready and following the Stanford University class on iOS developement with iTunes U.app and started to build a reference called "My iOS Dev Bible" with Apple's iBooks Author. What a wonderful piece of software.

This electronic book will contain essential things about various subjects: Objective-C, Xcode, Interface Builder, UIKit, etc. I plan to make the book available for download as soon as the content is more than good enough.