With the abolishment of Apple's iPhone developer NDA, the floodgates are open for documentation regarding the innards of the SDK. The first development instruction book to debut is Erica Sadun's "iPhone Developer's Cookbook, The: Building Applications with the iPhone SDK."
A description reads:
"single-task recipes for the full spectrum of iPhone/iPod touch programming jobs:
- Utilize views and tables
- Organize interface elements
- Alert and respond to users
- Access the Address Book (people), Core Location (places), and Sensors (things)
- Connect to the Internet and Web services
- Display media content
- Create secure Keychain entries
- And much more
The book is currently only available as a PDF, and is priced at $29.