I’m not going to post my opinions on why WordPress theme PHP files are required to be licensed under the GPL as many, many, many, people have done a much better job at it then I could ever do.
However I felt I had to write a blog post to point out something: I wrote some of the code that is currently being used in Thesis and I contributed it to the WordPress project under the GPL license. I overhauled a lot of the paged comments code originally contributed by Ryan Boren and others and added new functionality such as what comment page is shown by default or the sorting order of the comments themselves. It’s some of that code that I wrote that is currently in use inside of Thesis’
thesis_list_comments() function and I wouldn’t be surprised if there was more of my code elsewhere in the theme.
So not only is Thesis violating the GPL license, it is violating my copyright as I own all code that I have contributed to WordPress.
Just a little food for thought.