It is not free, $12.95 at the moment. This should do what you want. I will continue to seek an open-source alternative. I would really like to be able to have latex generated templates for my Keynote presentations. I especially want the ability to have something like the following picture, except I would want to use it as a template background for my slides in Keynote. All bullet points, pictures, and videos would be added from within Keynote. In essence, Xe(LateX) becomes just a template creator. Have a look, paying attention to what I call the "slide guide" in the header: