There is currently no easy way to do this on the built-in procedural devices. BigBen's suggestion would work to some degree although it would be a little tricky to setup. The Colour Adjust shader does only affect the color, not the displacement, but if you used it on a Power Fractal that then fed into the Displacement input of a Default Shader or the Shader input of a Heightfield Generator, etc. (all this within the Terrain group), then it should work.
- Oshyan