LEDs are the future of lighting but they aren't new.  British experimenter H. J. Round reported a light-emitting solid-state diode in 1907 while Oleg Vladimirovich Losev published the paper "Luminous carborundum [[silicon carbide]] detector and detection with crystals" in Telegrafiya i Telefoniya bez Provodov (Wireless Telegraphy and Telephony) but they were truly basic research and  no real work was done with them for decades.

In 1962, Nick Holonyak, Jr. of the General Electric company patented the first practical LED and by the late 1960s they were in common use.

Why did it take 40 years for LED Light Bulbs?  Mostly cost, just like with anything.  Although it wasn't until the mid-2000s that LED flat panel TVs came into the consumer price range, for example, they were debuted in 1977.

Here's a graphical history of LEDs. Let the age of better lighting begin (and don't buy CFLs)!

Via: Go Green LED Bulbs