Light-emitting diodes are the likely longterm replacement for compact florescent lights
Incandescent bulbs are disappearing. The EU will phase them out by 2012; the U.S., 2014. Some countries (e.g., Brazil, Australia, Switzerland) have already done so. The reason? Incandescent bulbs are inefficient; only about 5% of the energy they use is converted into light; the rest, heat. Incandescents last about 1,000 hours, more or less. Compact fluorescents are all the rage now in lieu of incandescents; they use up to 75% less power and theoretically last 10-times longer [lots of on-and-off has a tendency to shorten their lifespan]. Compact fluorescents have several potential problems: (a) They contain mercury, and thus should not be tossed into ordinary household garbage; (b) the lights flicker, which can cause problems for epileptics; and, (c) badly made CFL's can leak ultraviolet radiation (a potential cancer risk). Some folks do not like their spectrum either.
One of the more promising alternatives to CFL's are light-emitting diodes (LED's). LED's are made from two layers of semiconductor; by varying the properties of the layers, the spectrum of the light emitted can be modified. The light can be made similar to daylight, and they emit very little heat and ultraviolet light. Currently they are not cheap, costing 20-times the current price of CFL's; however, they last 4-5 times as long as CFL's, and 45 times as long as incandescents. It is hoped that as demand goes up, and manufacturing techniques become more efficient, the cost will drop. Mass produced LED's for the home are probably on the horizon as the replacement for the CFL, but when is uncertain.