Most of my career has been primarily in Product Management: New Product Development (R&D) and Software Development. I have been an advocate of the "Gating Process" as a way to bring products to market and have had a growing interest of Agile Sofware Development. Agile does away with the need for Project Managers (too much emphasis has been placed on PMP's) as being the lead, but rather puts the onus on the individual team members to set goals, take responsibility and deliver. I have now become an advocate of Agile and the idea of "Product Owners".
At first I took offense to a Scrum Master telling a Product Manager what to do. However since software delivery is a large part of what a Product Manager is ultimately responsible for the entire product then I am an advocate for any better of way of developing and delivering products. At the end of the day if Agile works then I am for it. This book does a good job of defining how the Product Owner should work in an Agile World, however doesn't describe all the other duties of the Product Manager ie Product Management: product marketing, product positioning, product lifecycle management, cross impacts of product introductions, and all aspects of the product. You will have to look elsewhere for this information. This book focuses more on "Product Development" rather than "Product Management". (Title should be Agile Product Development)
Remember at of the day as Product Manager you will be responsible for the product throughout the product lifecycle and ultimately the success of the product, so the sooner you embrace Agile Product Development the better off you will be.
A good book for highlighting how my manager should work as a product manager instead of a dev manager. The book explains in great detail the role of a product manager and the rules that they should work by in order to enable the scrum team to achieve great results.