It is used to implant a GPS-microchip in the body of a human being, using a high powered sniper rifle as the long distance injector. The microchip will enter the body and stay there, causing no internal damage, and only a very small amount of physical pain to the target. It will feel like a mosquito-bite lasting a fraction of a second. At the same time a digital camcorder with a zoom-lense fitted within the scope will take a high-resolution picture of the target. This picture will be stored on a memory card for later image-analysis.
(via Reality Carnival)
Elias was nice enough in the comments to point out that the ID sniper rifle was created by artist Jakob Boeskov and is not real. This site talks about the work but it is in German.