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.