The U.S. Army is using a British made "Talon Radience II hyperspectral sensor" on their UAVs. That's a mouthful, but what it does is simple. It's a technique used to find naval mines (the "bottom mines" that sit on the sea floor in coastal water). This system works by having the UAV fly over the route first to take a "before" picture. Then, after a time, when the UAV carrying the hyperspectral sensor is escorting a convoy, it compares what it sees this time, with what it saw the last time, and alerts the convoy commander to any changes in what is seen. The system uses software that ignore meaningless changes, and spotlights those most likely to indicate a roadside bomb. While this works fairly well looking for bottom mines, that's because there are decades of experience. Thus the initial use of the hyperspectral sensor on land will be for gaining useful experience.
UAVs are being equipped with more powerful sensors in order to deal with the special demands of the fighting in Iraq. The U.S. Air Force is trying out a sniper detection system mounted on low flying UAVs. This consists of an acoustic sensor, hooked up to a miniature computer that recognizes when a shot is fired below, calculates where it came from, and automatically swings the onboard camera around so that it is looking at where the sniper is (as indicated on the video.) This video is being broadcast to someone down below (usually the convoy, or unit, commander), who can then order troops to fire on the target, or take off after the sniper. Iraqis are not known for their marksmanship, and there are few real snipers fighting for the terrorists. But when someone does take a shot at U.S. troops, it's a good idea to shoot back (just to send a message, if not to kill the shooter), and even better to capture the shooter, and get more information on who he is working for.