Several years ago, the military was working on ways of delivering drugs via paintballs. We're not sure what ever happened with that (probably because they don't want us to know), but now the Army is interested in paintballs again, this time for detecting bombs.
The military has a bunch of clever ways of detecting explosives, including liquids and powders that change color in the presence of things that might blow up and kill you. The problem is getting those liquids and powers close enough to the thing you're worried about without having that thing actually blow up and kill you, which is where the paintball guns come in.
What the Army wants is some sort of system similar to (or identical to) a paintball gun that can splat bomb-detecting stuff onto a target anywhere from 50 to 100 meters away. It needs to be accurate enough to hit a 2' x 2' target with 90% probability at that distance, and it needs to dispense enough material that soldiers will be able to see whether that thing they just shot is dangerous or not without having to use binoculars. Oh, and the paintballs are also not supposed to set anything off by accident.
As Danger Room rightly points out, the thing about paintball guns is that they're not exactly precision instruments, especially as distance increases. To reliably hit a target at a hundred meters, you just sort of generally chuck fifty paintballs or so downrange and hope for the best, and the best often doesn't happen. There have been all kinds of attempts at making paintballs more accurate, but it's hard to escape the fact that paintballs are balls and as such, they're tricky to stabilize in flight. The military already has some bullet-shaped, spin-stabilized paintballs which are far more accurate, but they don't deliver enough payload.
So it's a tricky problem, but the military is hoping that you'll be ale to solve it, and if you can, there's a $150,000 grant in it for you.
Via Danger Room