|Agile Product Management with Scrum: Creating Products that Customers Love, by Roman Pichler. Addison-Wesley, 2010.
This is a fairly easy read (about 120 pages) explaining the role of the Product Owner in Scrum. I'd describe the target as "someone preparing to fill the Scrum Product Owner role who already knows something about product management." There is a little material on product management techniques, but it's not the emphasis.
This book is divided into six chapters, talking about the product owner role, envisioning the product, the product backlog, planning, the sprint meeting, and transitioning into the role. There's a good discussion of simplicity, and a little bit on handling this role on large projects.
I particularly liked that most chapters had a section on "Common Mistakes"; they gave me the sense of getting advice from someone who'd seen and worked through these things with real teams.