It's the exact same effect as when you excessively increase the sharpness control.
Just like this shot:
http://www.caps-a-holic.com/hd_vergl...ess=#vergleich
It seems like more detail as the grain appears more defined as does the detail on the light poles, but look at the edge enhancement ringing. Same thing going on in the Pitt image, but harder to see the ringing because of the shot. It's all just a sharpness illusion as high frequency artifacts are over-enhancing what's there.