My colleagues Ashwin Karkala and Govinda Sambamurthy have written a book about modeling and managing business services using the current version of Enterprise Manager Grid Control (11g R1). Nobody would have been better qualified for this task since they built a lot of the features they describe. I acted as a technical reviewer for this book and very much enjoyed reading it in the process.
Whether you are a current EM user who wants to make sure you know and use the BSM features or someone just considering EM for that task, this is the book you want.
The full title is Oracle Enterprise Manager Grid Control 11g R1: Business Service Management.
As a bonus feature, and for a limited time only, if you purchase this book over the next 48 hours you get to follow the authors, @ashwinkarkala and @govindars on Twitter at no extra cost! A $2,000 value (at least).