Spent all day fighting this, but I now have polygons working. To experience it for yourself, click through to the map, click on Peloponnese - BAM! Polygon.

While doing that I also ripped off an OpenLayers applet for creating polygons:
http://hcmc.uvic.ca/people/greg/maps/polygons.html

Now we can begin to create regional outlines for other areas, like Boeotia and Arcadia and so forth. There's a handy Wikipedia article on this precise topic here:
http://en.wikipedia.org/wiki/Regions_of_ancient_Greece