We know that light has mass and that beaming enough light at something can push it away - solar sails that will move a craft through the cosmos are based on this idea and NASA tested that concept earlier today when it launched NanoSail-D, a nanosatellite (cubesat) which will unfold to a 100 square foot polymer sail and travel in low earth orbit for a few months.

solar sail on a cubesat.
Sails?  We don't need no stinking sails.  Credit: NASA