The efficacy drops with junction temperature. Incandescent lamps are at 15 lumen/watt and CFL reach 40 to 50 lumen/watt. LED still has a long way to go and system efficacy are now reached up to 60lumen/watt. Key players like Nichia have parts in the lab running close to 200lm/Watt. There are single LED packages on the market like from www.luminus.com generating 6000lumen in one part. That is about 8 times of a 60W incandescent light bulb.

Problem is more the LED itself still has a 10cent/lumen cost. Many LED manufacturer are bringing more and more fabs online and with volume the prices keeps dropping. So far the Haitz law is still good for the LED world. In the next 4 years the LED illumination market in the US will go from couple million dollar to $5B per year and the 60W pulp replacement is expected to be around $16 retail price. Calculating the energy and invest cost a LED replacement in 4 to 5 years you will have an ROI of less than a year for LED light product.