[freerk]

Looks nice, but I am disappointed they choose Google Maps over OpenStreetMap for this :)

[jpatokal]

As far as I can tell, they're only using Google Maps for the display layer, the actual polygons are entirely theirs.

[rmc]

If you draw polygons based on what you see on Google Maps (or any other copyrighted map), your polygons might be found to be a derived work of the original Google Map.

Otherwise, you could just trace all the roads on Google Maps to make your own $BLAH Maps, that's obviously not legal.