Tim's site/blog runs a completely Flash front-end using WordPress as the content management system, so he has some experience making Flash and WordPress work together. You can even see the normal WP install at this URL.
On his PressConnect page he explains the necessary process of retrieving the data from the WP database and using PHP to format it as XML. This concept isn't exactly new, but Tim has done everyone researching the topic a favor by explaining the process in detail, creating a diagram, and posting some of the PHP code which interfaces with WP. Just another example of the Flash community giving back.