I just wrote an updated Heightmap effect.
It shades the underying image using a heightmap-derived (grayscale, white is high) bumpmap. Alpha is taken into account, so transparent parts of the heightmap do nothing to the underlying image.
Also, specular spot size and intensity are done as in the phong model.
I see some strange glitchyness in my videocard (vertical flickering lines) so please test it out, it may be a bug in my video drivers.
Heightmap plus Beta 1