At the foot of Little Round Top, near Devil's Den, there is a stream that runs through the valley. My guess is that is where the photograph was taken.

Right story, but wrong body. You're discussing another series of photos that have long been asserted to show a "dead Confederate sharpshooter." William Frassanito discussed these images at length in his books about photography at Gettysburg. The "dead sharpshooter" was actually an infantryman (possibly belonging to a Georgia regiment, as I recall) KIA while advancing up a slope about 40 yards or so from where the sharpshooter photos were actually made. Photos of the young man's body were made in the original location where he was found as well as at the "sniper's nest."

The ID of the man shown above remains unknown. However, the precise location of the image was finally discovered about 20 years ago by a local teenager who subsequently notified Mr. Frassanito.

If I'm not mistaken, this is a semi-famous photo because it's involved in one of the earliest known sets of "faked" pictures.

There was no Photoshop, the body is real, and the soldier is dead, but it's been suggested that he was an infantryman and not actually a sharpshooter. And there is evidence that the photographers (Gardner and O'Sullivan) actually moved the body from a relatively ordinary position at the bottom of the hill to the "sharpshooter's den" up higher ... why?

Because it was more picturesque and made for a more dramatic story.

[He can't be very high up - there's water all around him. He seems to be in a stream. - Dave]