The MQ-1 Predator is an unmanned, armed aircraft, primarily used for intelligence, surveillance and reconnaissance. They are often called an Unmanned Aerial Vehicles (UAV). The "M" means it has a multi-purpose role, the "Q" means it's unmanned and the "1" indicates it's the first of the series. The crew flies it from a remote ground control station.
It can be packed up and shipped on a C-130 aircraft and shipped anywhere in the world, including in theater in Iraq.
The U.S. Air Force provides these specs, as of September 2008:
General Characteristics
Primary Function: Armed reconnaissance, airborne surveillance and target acquisition
Contractor: General Atomics Aeronautical Systems Incorporated
Power Plant: Rotax 914F four cylinder engine
Thrust: 115 horsepower
Wingspan: 48.7 feet (14.8 meters)
Length: 27 feet (8.22 meters)
Height: 6.9 feet (2.1 meters)
Weight: 1,130 pounds ( 512 kilograms) empty 
Maximum takeoff weight: 2,250 pounds (1,020 kilograms)
Fuel Capacity: 665 pounds (100 gallons)
Payload: 450 pounds (204 kilograms)
Speed: Cruise speed around 84 mph (70 knots), up to 135 mph
Range: up to 400 nautical miles (454 miles)
Ceiling: up to 25,000 feet (7,620 meters)
Armament: two laser-guided AGM-114 Hellfire missiles
Crew (remote): Two (pilot and sensor operator)
Initial operational capability: March 2005
Unit Cost: $30.5 million (fiscal 1997 dollars) (includes 4 aircraft, ground control stations, and Predator Primary Satellite Link)
Inventory: Active force, 110; ANG, 0; Reserve, 0
Nov 19 Update: Here's an interesting article on the creative liberties taken with UAVs in the recent movie Body of Lies. (note: the article contains spoilers)
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