Seeing what Biscuits has just written, it looks like I was wrong in saying that a simulation needs a number of frames for a static pose. My excuse is that I've usually run simulations with Pose to Pose animation and assumed that VWD would read every frame in a Poser scene whether the figure moved or not. However, as Biscuits says, the program keeps simulating until you hit stop (when you choose to run a Static Simulation). The position of the cloth at that point is what gets returned to Poser.

(My other excuse is that I play with Physics simulations in other programs and get confused!)