An anonymous reader writes: Matt Mullenweg (the creator of wordpress open source blog software), after review by various legal experts, is sticking to his guns that themes and plugins that "extend" Wordpress violates the GPL if they are not themselves distributed under the GPL. Matt has gone so far as to post this on Twitter. Accoding to Matt, premium template called thesis should be under GPL and the owner is not happy about it. WordPress is willing to sue the maker of thesis theme for not following GPL licensing. The webmasters and thesis owners are also confused with new development. Mark Jaquith wrote an excellent technical analysis of why WordPress themes inherit the GPL. This is why even if Thesis hadn't copy and pasted large swathes of code from WordPress (and GPL plugins) its PHP would still need to be under the GPL. The Open Source / GPL vs Thesis debate continues further and some claims that Matt Mullenweg is anti-capitalist, the GPL is a communist ideology, and why users should moving away from WordPress.