Huh, just saw the new features videos, and they look pretty cool. Go and see, it is interesting.
http://www.luxology.com/ [luxology.com]

Pretty cool. A stack metaphor for building up modelling tool behaviour in the viewport.

I can see this as an amazing tool for someone customizing the behaviour of a tool then use that tool over and over again.

I think it would get pretty tiring if you had to manage the tool behaviour pipe stack all the time though.

It would be pretty cool if I had such delineation in say the Operator Type Properties to define how a tool behaved in the viewport while you were in the tool beyond what we have now with handles. Another folder beyond handles to define this as a stack.

For example, imagine binding a sculpt brush behaviour to your position parameters, a brush behaviour to color, a peak handle to move a prim that drove position, etc.