somewhat related.. I don't think it warrants a new thread, but I just ran across this on youtube.

http://www.youtube.com/watch?v=tTSnhhUA6V4

it's a new Fujinon variable ND filter system, mounted on a new 2/3 lens on a full sized camera. The variable filter looks like two disks (polarized?) mounted in a square box, fitted between the lens and the camera body, enabling full on/off with infinite variable ND capabilities. I haven't seen the product in production yet, but looks interesting.