Found this history of clipless pedals retrospective from JB's Love2Ride blog.
Did you know that the clipless pedal was invented in 1895?
Here's another fun fact - also in 1895, bicycle technology was advancing so rapidly that the U.S. Patent department had to open two offices, one for bicycles and one for everything else.
Photo is of an early clipless pedal design for mountain bikes by Scott USA in 1990.