Quote - It gamma corrects colors that get rendered, and it anti-gamma corrects color parameters entered into nodes, and images used in an Image_Map node. It does not gamma correct data coming from Fractal_Sum plugged into Bump or Displacement. It would gamma correct the output of that node if you look at it, i.e. you have it draw on your object. If the way you're using it is to control displacement or transparency, the data is not gamma corrected.

In particular, what I'm saying is that if a Fractal_Sum generates .5 at a given point and you run that into Bump or Transparency or whatever, the value used is .5, not .5 ^ (1/2.2).

thats a long a pretty long answer. 
didnt you in one thread say that we can not make displacement with the buil in GC because it gamma corrects it?