If I understand correctly what I have read, specular mapping is used to reduce the shiny plastic look. Specular mapping is to control the specular strength with a map, witch is possible in Poser 5 but not in Poser 4. That may be the reason we don't see it much. It seams to be state of the art in higher end apps. I would like to experiment with it, but unfortunately I have no idea how to create such a map. So I would also appreciate a link to a tutorial.