The iPhone Field Guide, version 1.1 is now in the wild. The update fixes a few typos, fixed a weird problem with the audio on a few of the screencasts, and added some new content. If you bought the book in the iBookstore, you'll see it listed as an update. Just press the download button and you're good. If you've been waiting for the PDF version, that's also now available.
I'm going to continue to update this book for a few years. The next big update will most likely be September with the release of the new iOS operating system. I'm also about to bump up the price so if you wanted to get it at the introductory price, now's the time.