I have a theme I downloaded on WordPress.org (http://wordpress.org/extend/themes/darkblue)
I have read this blog post: http://wordpress.org/development/2009/07/themes-are-gpl-too/
However, in the zip files of these themes, there is no license.
Also, I see GPL on the bottom of the site, but it doesn't specifically clarify if all wordpress.org themes are GPL.
My question is, are themes like Darkblue GPL unless otherwise specified? Because I'm interested in basing a theme off it.