Although LED's are already much more efficient than incandescent lights, they're still less efficient than good fluorescents, or sodium vapor lights. Most of an LED's inefficiency is getting electrons to move easily from the metal wires that power the diode to the semiconducting material that gives off the light. "Resistive barriers naturally arise at that metal-semiconductor junction. Although superior to conventional technology, that resistance causes LEDs to heat, wasting energy and shortening their lifespan. The UF researchers replaced the resistant metal with a carbon nanotube film... To the researchers delight, their experiments showed the nanotube films had about one-third of the resistance of the industry standard metals..." This will both make LED's more efficient and increase their already-impressive lifespans.
Currently carbon nanotube films are too expensive for this to be an economical design, despite the efficiency gains; however, in the next decade it is likely to become commoditized just as carbon fiber was, and the invention will then become a viable household technology.