Here in Washington State there has been a huge push to LED signal illumination, I believe for both operating and maintenance costs. The power savings, as spread over the state, are tremendous!
The sudden "snap" effect also caught my attention a few years ago and sure enough it was a LED head.
Another interesting item I spotted a couple of months ago was a red LED beacon mounted atop a "STOP" sign and it was solar/battery powered! Definitely needed where it was, too- the sight distance was terrible on approach to the intersection. I would like to see more of these in use.
