Presumably, he's annoyed that he distributed a piece of software under the terms of the GPL, and others extended it and sold those extensions under proprietary terms. If this was ffmpeg, we wouldn't even have to wonder about it.
To expand on your comment - Matt Mullenweg is often quick to point out that WordPress itself came into being by forking a GPL'd abandonware project. It's because of this that I think he genuinely wants to ensure users of the software have the same opportunities he has had.
Also, regarding the marketplace surrounding WordPress, WooThemes distribute their themes under the GPL and per Andrew Warner's interview with co-founder Adii Pienaar (http://mixergy.com/woothemes-adriaan-pienaar/) they make $2+ million a year and have had some of their code incorporated back into WordPress by Automattic. This should assuage any fears about GPL themes being commercially viable and of Automattic taking a dislike to others making money off of WordPress.
tptacek|16 years ago
andrewtj|16 years ago
Also, regarding the marketplace surrounding WordPress, WooThemes distribute their themes under the GPL and per Andrew Warner's interview with co-founder Adii Pienaar (http://mixergy.com/woothemes-adriaan-pienaar/) they make $2+ million a year and have had some of their code incorporated back into WordPress by Automattic. This should assuage any fears about GPL themes being commercially viable and of Automattic taking a dislike to others making money off of WordPress.
photomatt|16 years ago
http://wordpress.org/extend/themes/commercial/
All are GPL.
dan_the_welder|16 years ago