I'm pretty much finished with my new rig and now started skinning the bloodelf model. It looks like I got the bone placement and model topology right, so things are coming together pretty well and fast so far.
Here's a quick look at the breast-setup and how it works. The jiggle amount isn't final though and probably will have to be adjusted for each scene individually.
Note the purple box right in the center of the screen, which is my reference spring. There are also purple arrows pointing in four directions - these are gravity helpers. Depending on the direction and distance the reference spring moves, it activates and controls the strength of various gravity helpers, which only affect the springs in the breasts. The entire thing is automated and that's how the breasts move a bit more naturally, rather then strictly following the character's direction of movement.