So this is all pretty straight forward. The actual process of it is based off of Anselm's Pflow tutorial from back in the day and that Projection table in Avatar. All I did was change it from scaling on Z to displacing it's Z position based off of the color values. I'm using an AddMultiply Helper to do just that to the color values.
I used a standard Material who's position was rotated so that the lower it was the bluer. The middle - green, the highest points red. Also, it may look like there is flickering from the render, but if you look close you can see the cubes jumping a bit. This is caused by the compression from the terrain map. I like it though, it's gives it a more natural feel to the movement.
The InMesh is using a Cylinder which deletes particles outside of it to create the circular cutoff.