Added some quick and dirty colors. Also pushed the quality to 1024x1024, just to see how it would look. Turns out to look amazingly-detailed...too bad it takes about a minute to generate (this is still CPU-side).

When I say quick and dirty, I mean it. Height colormap + perlin dirt map computed per pixel. Ouch. 5 KB pixelshader. Bigger ouch. But that's the beauty of prototyping! You don't have to be efficient about it. Took all of 5 minutes to write the shader for this.

The last image is only a 512 grid, for reference. The others are 1024.