Yes, it is photoshopped. Also it looks like there is some bleeding of one of the pictures going on on the top left, with the linear movement of the stars. There should be no question about whether NASA will show manipulated imagery on their daily feed.
As for this technique, four flat pictures will be joined and then cropped to show you the movement of the celestial sphere above us.
it may be color enhanced but that's a typical 360 degree panoramic images used for making virtual environments.
There is definitely something about the colors, although this may be due to the exposure only. The bright blue small streaks and dots on the right side of the lake is interesting though. This might be fireflies?
Steve actually showed a similar effect (panoramic flat sky => panoramic circular sky) where the sun never leaves the sky using panoramic photography (The Midnight Sun - Concave Earth / YouTube):
This is in the caption:
Stars far in the distance appear to show unusual trails -- as the Earth turned -- because early exposures were artificially faded.
Does this make sense? Key words are unusual and artificial.