From a NBC Bay Area report, “ SJ, Oakland Airports Ranked High for Laser Beam Pranksters“, pointing laser beams at commercial aircraft is a dangerous prank and doing so is a federal crime. 1,251 strikes on commercial aircraft in the US were reported in 2010.
This video from Seattle shows that police can track down pranksters from the sky. I doubt that the pranksters know how easy it is to be caught in the act.
Dale Dougherty 