Lois Greenfield's Antigravity Dance Company.

From the website:

I had some of my favorite gymnasts doing somersaults in a circular formation to evoke the internal workings of watches. The maneuver was not especially difficult for such talented performers: the challenge was in coordinating the timing of each gymnast and the height of each somersault so that they would form a circle in the air.

See more awesome photos by Lois here: http://www.loisgreenfield.com/galleries/index.html