What an amazing journey! When we set out to write a book on iPhone development, it was purely a labor of love. We never dreamed our book would end up in so many people's hands. Just imagine, our little book, available around the world. Who'd of thunk it? This wave of interest took us completely by surprise. And, of course, we are delighted by every bit of it.

So, what's new with this edition? Lots! For starters, we've gone through every single line of code and made whatever changes were necessary to bring each project into line with SDK 3. As you'd expect, we've gone through the text, too, so the explanations are all up-to-date. We've also gone through the errata from our Apress web page and the errors reported on our own web site, http://iphonedevbook.com, and we've done our best to scrub each and every error from the book. Of course, nothing is perfect, so please do report any errors you do find so we can continue to update the book through each new printing.

Is it worth buying this book if you already own the first edition? This is an excellent question that has spurred many a conversation with Apress and between the two of us. There is a lot of subtle new material, including a new project that introduces Core Data, which is an important persistence technology that has made its way to iPhone. In addition, many of the discussions have been clarified in an attempt to make some of the more complex topics a bit easier to understand.

We've definitely made the book better. If you've already been through the first edition and feel very comfortable with all the material, go ahead and move on to More iPhone 3 Development, which takes up where this book leaves off, discussing the amazing new technologies introduced with SDK 3.

If you haven't made it through the entire first edition yet, if you feel a bit fuzzy still, or if you just want to support us as authors, then by all means pick up this second edition. We do appreciate your support. Be sure to check out http://iphonedevbook.com, and drop us a line to let us know about your amazing new apps. We look forward to seeing you on the forum. Happy coding!

Dave and Jeff