Weight mapping is another way to rig poser figure. It's a better way to discribe how a joint should bend, which polygons go where. At the moment, only very few figures use weight maps for bending - some of the figures which come with p9/2012 do and there is already a weight mapped version of Antonia. A weight mapped V4 is in the works. 

Weight mapped figures potentially bend better as figures with the older deformation zones. As a bonus, weight mapped rigs can be tranfered very easily to new clothing and require less work, so creating conforming clothes for a weight mapped figure will be a lot easier. 

The process of creating a weight mapped rig is time consuming, though, so it will take a while until most figures are re-rigged.

Were the words slow and small enough?

A ship in port is safe; but that is not what ships are built for.
Sail out to sea and do new things.
-"Amazing Grace" Hopper

Avatar image of me done by Chidori.