Conclusion… the boomerang reacted just the same under zero gravity as it would be on the ground. Aerodynamics expert David Caughey of Cornell said that the result is as expected; the looping paths are the result of uneven forces on the curved devices by the air they travel through… not the influence of gravity. [Newscientist]

The boomerang was working in the space station, but would not work in the real space though. Boomerang expert and designer Gary Broadbent said that a boomerang would not work in the vacuum of space, as air molecules are needed to generate the lift to make the boomerang turn. [Universetoday]

Boomerang experiment at International Space Station from YeinJee's Asian Blog