Adiabatic switching is the technology you're thinking of. There's been some research in this area, but I'm not aware of a working product. My suspicion is the silicon area requirements are too high. However with the current design nodes of 90nm and lower silicon area isn't as much of an issue with *some* designs as it used to be.

http://kabuki.eecs.berkeley.edu/~luns/papers/241re p.html

-John