Well, it's hit the "law enforcement" market in ex-Soviet Georgia...
http://www.youtube.com/watch?v=X4UM6vuEf4o&feature=player_embedded
Here is a better background on LRAD weapons:
http://science.howstuffworks.com/lrad1.htm
The earliest documented use of LRAD in the field was in the first Gulf War, in 1991, where it was used for crowd control and dispersion.
A company named Maxwell Technologies got a patent on an ultrasonic directed sound weapon in 2000. The company says it can cause eardrum rupture at 185 decibels (dB), pulmonary (lung) injury at 200dB and death at 220dB. (so they quite literally are speakers to die for...)
The Brits developed a device code-named "Squawk Box" in th eearlie 1970's that, utilizing 2 HF beams, produced a highly precise beat frequency in the infrasonic range (about 2Hz) that was so focused it could target a single person out of a crowd...
The history of sonic weapons is very shady and secretive. There are a LOT of myths, conspiracies, and high-weirdness out there. But the REALLY weird stuff often comes in the form of documented and deployed devices.
But for something COMPLETELY different, my favorite "sonic warfare" story is this one:
http://www.youtube.com/watch?v=8I3zCQzZx68
--Richard