Spheres -> weight maps would be trivial. After all, Poser and DS are in effect doing it already, it just needs to be output to a vertex map (which is just a list of values for each point). However, I believe that many if not all weight-mapped systems use a single set of weights per joint while Poser rigging has separate weights for each parameter - however, even if that's true there's no reason a new system shouldn't use a map-per-parameter (if you wanted the same values in each it would be a simple copy and paste at worst, and perhaps just a tick-box at best).