Gamification by Design co-authored by Gabe Zichermann and Christopher Cunningham is the first book I have read on the subject. Until now, the most entertaining thing I had read about gamification was an article by Ian Bogost.
Zichermann and Cunningham do a great job of introducing the reader to gamification. The clarification on what it is not comes in the Introduction - it will not help move bad or poor products. They use the metaphor of cake and icing to describe what gamification can and cannot do for you. A great icing job will entice someone to bite into the cake but it will not make them bite twice if the cake is not up to par. Gamification is icing on the cake.
The authors cite examples of success and failure with gamification through out the book to illustrate specific concepts. Each of them offer fascinating insights into human motivation. In the context of gaming in education, they argue putting education ahead of fun makes it less effective and actually impedes the process of learning. As a parent, I can attest to this. I have yet to come across a piece of edutainment software that was a big hit with my child in the way games like Angry Birds or Temple Run have been. As the authors say "Kids could smell the shift from fun to work a mile away". That is certainly true in my experience.
If you want to learn how to think about introducing gamification into web and mobile applications, this book is for you. This is not a game development cook book but there are a few tutorials to get you started. A technology background would make this book easier to read but is by no means essential.
My only quibble with the book would be the examples selected in the chapter Gamification Case Studies.It would be nice to see more offbeat examples of gamification in action - where companies have utilized gamification very subtly and been highly successful. The Yahoo or Quora models don't translate widely. Foursquare is a great gamification example but is in a niche where it works well. I was not able to see how any of that may translate to an insurance or brokerage firm for instance - businesses that are not the most "natural" fit for gamification. Even so, I am very glad to have learned how to think gamification and would highly recommend this book.