Is this really the "official" book? Official usually means that it's endorsed by the company that makes the product but I've never heard of Apple giving any publication "official" status.
I grabbed these two products but haven't had the time to check them yet:
I reckon it's news because it's a new book from a different author and publisher?... I generally find O'Reilly's books to be more to my personal taste than books on the same topics from other publishers, so I for one was happy to see this announcement.
I believe it was the NDA that was preventing publishers from releasing iPhone native application development books.
Since the NDA has been lifted to allow people to openly share iPhone development knowledge (only for APIs that have been released in public iPhone updates), that should allow everyone from book and magazine publishers to bloggers and tech conferences to share such information.
I feel Beginning iPhone Development is good because it helps build your confidence so that you can work on getting through your own projects and Aaron Hillegass' book. This book seems more advanced, and I will go get a copy this weekend.
Aside from learning from $30-40 books: Building a calculator from scratch was recommended to me and is a great project that you can go from basic (accumulator) to nuts (Quartz rendering) on.
I grabbed these two products but haven't had the time to check them yet:
http://www.pragprog.com/titles/amiphd/iphone-sdk-development
http://www.pragprog.com/screencasts/v-bdiphone/writing-your-...