From Wired's Danger Room blog:
"The number of flying robots in the American armed forces' arsenal has gone up by nearly 1400% in four years, military documents show. A relatively-modest unmanned fleet of 217 machines has grown into a 3211-drone armada.
Most of the change has come in small, handheld unmanned aerial vehicles (UAVs) -- ones weighing 10 pounds, or less. In 2002, there were only 90 of the machines, used to peek around a corner or over a hill for enemy activity. By late last year, there were over 2800. The most popular of these UAVs in the Army's three-foot-long Raven. It weighs about four-and-a-half pounds, and good, hard toss will get it airborne, where it can loiter for a little over an hour, at nearly 1000 feet."
Read more here