It's called the Amanar.  And it's fierce.  The move consists of a round-off onto the springboard, a back handspring onto the horse, a flip off, with a 2 1/2 twisting layout back flip finish.  Only a handful of gymnasts in the world can pull off a vault of this magnitude.  Lucky for us, most of them are on the U.S. Olympic Women's Gymnastics team.  McKayla Maroney was chosen to compete in this summer's games because of her strength on this stunt.  Check it out!

 

McKayla Maroney's Amanar vault

Amanar U.S. compilation

In slow motion: