Laser Guns shoot laser beams and watches for the reflections to bounce off your car. (officers are trained to shoot at mainly headlights, license plate, grille because of high reflectivity) With that being said, it's almost impossible to block light from reflecting back, so instead of tackling that, the laser jammers shoot laser out to be detected by the gun. By doing that, it confuses the gun and throws off the timing to the point that the gun can no longer read the "reflections" and therefore the gauge the distance. It is illegal to use in California, among many other states.
What is good about these things is, it gives the driver warning while it jams the target, giving the driver enough time to slow down. When the driver is below the posted limit, he or she can decide to turn it off so the speed of the vehicle can be properly detected and shows the officer the right speed.
The police, as well as the rest of the media, want the public to think that these devices never work. Well, it isn't a cheap offering to play with speed. $500+ at least for a decent unit. There are only three companies still left in the business that produces working jammers. Blinder M27 ($479+), Laser Interceptor ($599+), and Cincinnati Microwave/Escort ZR4 ($450). The most effective being the Laser Interceptor, which can run up to $3000 for a full high intensity 99% bullet proof install for front and back protection. Blinder is second, and Escort is third.
There's a whole forum dedicated to this stuff that I just found.
http://www.radardetector.net/
And for your bike, there's the Cheetah M27 Bike kit for $500 that provides both front and back coverage as well as a in-helm alert mechanism. I don't think its really necessary for one, because laser tickets are easy to argue given the small size of a bike. The beam is more than 4 feet wide at 1000ft and 2 feet wide at 500ft, so the officer could easily be aiming at a nearby car instead of the biker.