Report on LED lighting points to technology being mainstreamed.by 2015

Lit Up: an LED lighting field trial - by the Energy Saving Trust suggests that LEDs will dominate the market by 2015.

http://www.bbc.co.uk/news/science-environment-16199552

http://www.energysavingtrust.org.uk/Publications2/Energy-efficiency/Lit-Up-an-LED-lighting-field-trial

Note: the LED case is not wholly clear cut. The energy saving, and the longevity of LEDs are massive advantages.  There have been questions about the composition of the white light - with some research suggesting that the proponderance of blue light may interfere with producation of melatonin which regulates sleep cycles.