[link|http://www.usatoday.com/tech/news/techinnovations/2005-04-14-led-lighting_x.htm|LED evolution could spell the end for light bulbs]
Just this week, researchers at the Lighting Research Center at Rensselaer Polytechnic Institute in Troy, N.Y., said they had boosted the light output per watt of a white LED to almost six times that of an incandescent light bulb, beating even a compact fluorescent bulb in efficiency.

The current generation of mass-produced white LEDs is not as effective. It's about twice as good as a light bulb of the same wattage, but the energy savings aren't enough to overcome the major drawback of being expensive.
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But development is brisk, and the Department of Energy has estimated that LED lighting could cut national energy consumption for lighting by 29% by 2025. The total savings on U.S. household electric bills until then would be $125 billion.