John Villasenor has written an useful article called, What is a Drone, Anyway, in the Scientific American blogs that guides the reader through the distinctions between: drones, planes on autopilot, unmanned aerial vehicles, remotely piloted aircraft and first-person view unmanned aircraft. We're becoming increasingly used to seeing drones in use in conflicts such as Afghanistan and Iraq, and their use is spreading to civilian law enforcement and border patrol, so its a good idea if we understand the jargon.
A drone is an autonomous arial vehicle that can fly without human intervention from point A to point B, or they can patrol a given area or perimeter. If the drone is armed, like the US Reaper drones, then traget acquisition and weapon firing is under human control. However, in a very worrying development South Korea has developed sentry robots to patrol the DMZ between it and North Korea that are capable of identifying targets and firing without human intervention. So the prospect of totally autonomous lethal drones is certainly here! Ron Arkin at Georgia Tech has recently written a book called Governing Lethal Behavior in Autonomous Robots to explore the important issues these development may lead to.
By the way, Scientific American has some very interesting blogs, I encourage you to check them out.