The Kindle Edition of the book is now avaible for purchase from the Amazon.com on-line store. Here's the link.
As I've mentioned previously, the iBook version of the book for the iPad is definitely the definitive edition of the book, but if you have a Kindle ebook reader, this edition is a good alternative. The content is mostly the same - there's just less interactivity and a few less images in this edition.
I appreciate everyone's support in this project, and I hope you enjoy the book.