Product Owner role in Agile Teams.

I am currently working on my assignment (from Oxford University) Adopting Agile in a project and while doing that i started wondering as to what exactly is the role of the product owner? What does a prodcut owner do, day in day out. I came across a few points after searching for product owner role on the internet.

• As the Product Owner you're responsible for the features that get delivered.
• You own the Product Backlog.
• Plan one iteration ahead of the developers.
• Prioritise effectively so that you get the biggest bang for your buck.
• Identify what is valuable to your company and find out the cost of each backlog item by getting provisional estimates from the development team. Then prioritise.
• Managing expectation between the business and the project team.

Is that it? Is that all what a product owner does and gets paid a huge sum of money for? Let me know if anybody out these has any other pointers.