This is an in-camera double exposure shot this past Wednesday, the night of the Harvest Moon. Both exposures were shot with a 70-300mm Nikkor lens on a Nikon D90 body. I first shot the moon at 300mm (450mm on my D90) and, remembering where I had place it (in the upper left slightly), I then recomposed for the boat shack and made the second exposure using the same lens but set at a wider focal length. Both shots were made on a Manfrotto tripod.
The camera did all of the exposure work for me (halving the exposure for each of the two frames), but I did set the camera to -1 stop of exposure compensation to keep the shot somewhat on the dark side (mainly to hold detail in the moon). I shot the scene in RAW (as always) and adjusted both exposure and color balance a bit during editing.