This is very clever. :)
http://pinns.co.uk/osm/docs/multicolored.pdf
http://pinns.co.uk/osm/typwiz4.html
Anybody try typwiz 4 yet? He is using the same trick to create multicolored bitmaps that I've used in my own maps for a number of years (stacking duplicate polygons with transparent bitmaps), but this simplifies the process.