A few additional notes:
The Fosbury Flop was developed independently by Canadian Debbie Brill, who called the jump the Brill Bend. Brill, a two time Commonwealth Games gold medalist (1970 and '82), was the first woman jumper from North America to clear 6 feet, and is the co-holder of the Commonwealth record (1.98m, set in '84). Although a top competitor throughout the '70s and early '80s, she never placed higher than 5th at the Olympics (in '84).
The Fosbury Flop is unique amongst field events in that it utilizes a curved run-up. The curved approach lets the athlete begin the leap with body leaning away from the bar, allowing him/her to simultaneously affect a vertical take-off (maximizing the amount of height generated from the energy put into the jump) and begin a spin about the bar (allowing the feet to clear the bar on descent).
The main reason the flop is superior to previous high jump techniques (straddle, scissors, Eastern cutoff and Western roll) is that it allows the athlete to jump with a lower center of gravity, meaning more height can be cleared from the same energy input. It's possible for a jumper's center of gravity to pass beneath the bar using the Fosbury Flop technique.