I couldn't play with the new builds in the past days, that's a bummer really; maybe this weekend I will model a desert eagle just to complete a character I sculpted a while ago, so I should be able to test the latest MM build a little more.
The pin movement works great, I have experienced some strange behaviour though:
a) moving the pin outside of the model (like you would do with the warp tool) ends up with the pin actually jumping inside of the model itself;
b) At one point the pin handle wasn't moving anymore; maybe the operation became too heavy (I suspect that was the reason because cancelling it and doing it again worked), but I'm not sure if that was the actual reason. Should l be able to replicate it I'll make you know.
Another odd thing is that after you set a target there's no object selected and the import menu appears once again. I'm not complaining, just wondering if that's intentional, considering that I tried to import/replace all the primitive objects (bunny/sphere/plane) and I got appended instances instead.
Talking about warp, an old feature that I probably didn't addressed in the past is the fact that the transform operation on selected faces actually ends up in an extrude action (sort of actually, but the end result is very similar). Warp, on the other hand, gives you a pinch handle that moves faces with a falloff inside of a selection.
What if, after you use a transform operator on a face selection, the near faces of the selection are influenced with a smooth falloff outside of the selection, basically a warp where the selected faces are the equivalent of the pin handler?
Anyway, from what I tested until now you did a terrific work as usual. Nice job RMS.

@MagWeb: man, that dummy workflow is neat. In a way it reminds me of Zbrush mannequins.
I didn't have the time to try it, and I would probably prefer to use a base skinned model to pose and import for sculpting, but the idea is very clever.