Boeing 501 Heavy Experimental, the ATC call sign of the first flight of the 747-8F lifted off runway 34L of Paine Field in Everett, Washington, USA, at 12:39pm PST (20:39 GMT). Smooth and silent.
Congratulations Team Boeing.
For live video of the landing, visit the Boeing 747-8 first flight site. Follow the flight live, here.
Update 1
N747EX lifts off from runway 34L. Click on the image for a high resolution view. Observe the initials of Jack Waddell, the pilot commanding the first flight of the very first Boeing 747 on February 9, 1969, on the nose gear flaps.
As the sun returned over the horizon, RC501 calls sign Boeing 501 Heavy Experimental, returned home to Paine field.