There are about a hundred Scrum Master courses for every one Scrum Product Owner training course. Yet the product owner is an absolutely key role in agile/Scrum projects. During the Agile 2008 conference, some people from Innovel presented on the product owner role and have made publicly available some great material for training product owners. It's a hands-on role playing exercise based on a hypothetical product called Beer Miles, a credit card that gives users reward points for purchasing beer from participating retailers. The product-owners-in-training are presented with a business case for the product and a set of product capabilities (aka user stories or features) that they must categorize and prioritize.
Cheers to the folks at Innovel that made this available!