I've now bought the Kindle version of this book, and 2 items were downloaded to my Kindle (actually, the Kindle software on my iPad) -- (1) the book itself, and (2) a note from Amazon with my unique access code.
Just an FYI - I was nervous to buy a book with an access code on Kindle, but went ahead because I didn't see anyone on forums/comments with issues. However, they emailed me a code that did not work. It was emailed, not sent to my Kindle. I have contacted customer service and hopefully they will give me a new code.