The Facebook Marketing Book, by Dan Zarrella

Facebook Marketing is not a book for programmers. For us, it's a very hard read and finishing it took some determination. Neither it is for startups that intend to be the next Zynga, as it offers little advice for those, specially with regard to monetization options. It contains, however, good advice for already established entities that want or need to use Facebook as a vehicle for engaging current and acquiring new clients that's specially valuable if you are new to the social networking environment. It also contains an overview on how to employ Facebook's functionalities as tools to promote your brand, for communicating and organizing social events and on what kinds of content you should generate to keep your Facebook assets alive. It offers some advice that's useful for hackers like me, on how to best model the social relations of a Facebook application to ensure it has chances of becoming viral.

You can find more about the book on O'Reilly's site and on its Amazon page.