Metafilter links to and discusses to an interestin g article in EE Times about a researcher at Rensselear Polytechnic Institute wh o claims to have invented a 99%-efficient omnidirectional reflector that will allow LEDs to replace light bulbs. Since lighting accounts for about 25% of US energy use, efficiency gains here can have a huge impact. NSF and ARPA are bankrolli ng the research, and the research team hopes to commercialize the technology in three to five years.

Wikipedia has a nice general background article on LED technology.