Weight-mapping, if it's a single-skin solution (which DAZ have said theirs is and so, if we build on BB's comment, presumably Poser's will be) means that any bone can affect any part of the mesh - no more having to use body handles or morphs to get skirts and the like to work, and things like webbed hands and bat-wings that join all the way down to the hip become possible. Also, a weight-map can be arbitrary making it much easier to do things like epaulettes where part of the shoulder mesh needs to move and part needs to stay put (though the new P8+ falloff options should also help there).