Requires latest version of my OpenSCAD Bitmap Module: http://www.thingiverse.com/thing:2054

This is just an example of how to do a height map. Now I just need to write a script that takes maybe a grayscale image and converts each pixel into the bitmap array to pass through this script... (think terrain data)

You can pass an array on the command line like this:

/Applications/OpenSCAD.app/Contents/MacOS/OpenSCAD -m make -D bitmap=[2,2,2,0,1,3,2,2,2] -D row_size=3 -s height_map.stl height_map.scad