I have been working hard at developing an understanding of what it means to be a product manager how to do this.  A part of the role has been to step in as an XP customer.  Recently I had a great IM conversation with Dan North about what the role is all about, and how to best do the job.  Dan was my XP coach when I was working on a project in London, is the father of BDD, one of the lead developers behind JBehave, and RBehave and an all round great guy.

Here are some of the highlights of what Dan had to say:

Focus on your outcomes.

Work out what it is you want to achieve, and how much you think that's worth.

Everything else is detail. If the project goes "over budget", it just means you didn't predict the future. As long as you're within your comfort zone for the benefit you're going to get then you're still ok.

Likewise the feature list is just detail as long as you and the development team are on the same page

The most useful thing you can do is inspire the developers with your vision.  Ideally find a way of sharing any success, so they feel vested in the outcome

Try to stay focused on the "what". As a techie, you will be really tempted to get involved in the "how",but you have to trust the team to do the right thing. Once you let go of the technical detail you can really get into "character" as a product manager!