Prisons have a well-documented problem with inmates using small quadrotor drones to sneak contraband in. Since posting guards with #8 birdshot doesn't seem to have been working, the US Federal Bureau of Prisons is now looking for a less redneck solution.
The Bureau of Prisons has issued a Request for Information -- a government way of saying 'I want to buy this thing!' -- for some kind of system that "allows for the detection, tracking, interdiction, engagement and neutralization of small (less the 55 LB [25kg] total weight) unmanned aerial systems."
It doesn't specify how the system should work, just that it should be capable of detecting a UAV intrusion, tracking it, classifying a UAV as a threat, and 'responding' appropriately. The system would have to work on UAVs up to 5500m, which is well above the range of most current consumer UAVs, and at the limit of what can be easily hacked together.
Anti-drone systems are having a bit of a moment, with systems ranging from targeted malware, radio jamming and giant airborne nets all under development. The Bureau of Prisons hasn't specified what kind of system it wants: jamming radios is probably safer and less intrusive, but I'm equally sure they wouldn't say no to some kind of mini anti-drone Gatling gun.