The Google Maps API for Flash now has Styled Maps. If you want to use the new feature download the Maps API for Flash SDK 1.20 or later, and refer to the Styled Maps section of the documentation.
ScribbleMaps has quickly added the option to style maps. So if you want to have a play with the new feature go to ScribbleMaps and click on the 'Style Map' option.
Via: Google Geo Developers Blog