Andrew Goodman's book is finally out. It's called Winning Results with Google AdWords and it's chock full of AdWords info.
This book is detailed, and covers everything from the history of Google and AdWords to ROI, conversion rates, and metrics for your AdWords campaigns. It even mentions Orkut(!).
The best part of the book is Andrew's straightforward philosophy, and if you read it through, you will be able to focus on creating AdWords campaigns that will really impact your business. You'll also be able to pass the AdWords Professional competency test if you read carefully.
Andrew also is the author of a very useful ebook (that costs $65) called: 21 Ways to Maximize ROI on Google. If you haven't bought the ebook, buying his new paperback book will give you most of the key information, and since the "Winning Results" book costs under $25, it's a very good deal.
In summary, a detailed and wide-ranging book on AdWords and online marketing in general. Check it out!