I make iPhoto slideshows using Lion, and they include maps of the cities/towns/places I've gone, complete with music. But in Apple TV they didn't show up. I had to export them as a movie into iTunes (can be done from within the slideshow easily, you cannot just export it to desktop and drag it, it must be converted into a movie format first). It takes 15 minutes and there it is. Just in case anyone else had trouble with that.