Boeing leads the way in developing laser weapon systems for a variety of U.S. Air Force, Army and Navy applications. These systems include the Airborne Laser, Advanced Tactical Laser, Free Electron Laser, High Energy Laser Technology Demonstrator and Tactical Relay Mirror System.Having worked on some of the Star Wars stuff back in the day, I can tell you that making it actually work as advertised was more of a timing challenge than a technological one.
The congress, dominated by Democrats, didn't want the Soviet Union to think we were acting too aggressively toward it. The President (Reagan) was industriously banging away at their foundations with any sledgehammer he could lay his hands on. The ground-based laser system decsribed at the link traces its ancestry back to the R2D2-like air defense systems now mounted on most Navy boats. The Armys version was a 40mm gun on a tracked vehicle with a radar to direct it, and a computer to prioritize targets called DAVID. The review of the DAVID systim I saw showed a very aggressive system that would find anything that moved in the air, point the gun at it, and demand that the operator either pull the trigger or designate the target as friendly. Operators were warned to fasten their seat belts securely, because the machine didn't waste time moving from one potential target to the next. When they said "neck-snapping speed" they weren't kidding.
Recent versions of this have been able to pick off targets down to small mortar shells and RPG rounds, as moving mirrors and prisms is easier than swinging a 40mm gun barrel. It would seem that the target acquisition system is about ready for showtime, and the laser is quickly catching up. It's not that big lasers are difficult to build, as such, but that the support systems for them are prohibitively bulky. Progress is being made here, too.
If Boeing wants to do a real-life test, they could park their system just north of the Gaza border with Israel, and take pot-shots at the Iranian rockets Hamas is launching. If this works, they will quickly be able to expand to shooting at the mortar shells Hamas will certainly be aiming at their test rig, too.
H/T to Bijou Renaissance Man, who has some further details and pictures.