So what's so awesome about LEDs?
Well they're much more affordable now, and they last a long time. With average usage, 1 LED light bulb can last upwards of 40 years, saving you about 25 replacements of your standard incandescent bulb (that's that same technology we've been using for the last...hundred years).
Also they're way more efficient. Incandescent bulbs on average release 90% of their energy as heat. LED efficiency is constantly improving, but right now, on average, they use about 75% less energy than your average incandescent bulb.
So widespread use of LEDs has a huge potential impact on our energy savings here in the U.S. The D.O.E. estimates that potential electricity savings equal to the output of 44 large power plants. That's about 30 billion dollars worth of energy in today's prices.
1"LED Lighting", U.S. Department of Energy, Energy.gov
2"How Energy-Efficient Light Bulbs Compare with Traditional Incandescents", U.S. Department of Energy, Energy.gov
3"Lighting Basics", Bulbs.com