I've spoken out in support of Matt Mullenweg, WordPress, the GPL, and general open source community principles before. It seems like we keep having this discussion, and that it often degenerates into a battle of personalities.
Here's what I continue to believe about licensing and the GPL, which started as a comment on Why the GPL does not apply to Premium WordPress themes, which is part of the #thesiswp running battle. For context, you may also want to watch the Chris Pearson / Matt Mullenweg interview.
Bottom line: Themes and modules are derivatives and should be licensed under the GPL. You can use trademark and other non-code protections that will let you sell them and limit distribution if that is your chosen business model.
The rest of this is the comment I posted.
The way that PHP is executed means that everything runs together in the same space, with no separation (this is a simplification, but essentially correct). So, not the same as the red herring about software apps and operating systems (this comes up all the time).
The Drupal community generally agrees with WordPress in that all themes and modules are derivatives and thus must be licensed as GPL *if* you distribute.
Luckily, themes have CSS, images, and other pieces which can by copyrighted/trademarked and licensed in whatever way you see fit. The legal page on the Drupal-focused TopNotchThemes site makes this nice and clear:
- Drupal is open source software covered by the GPL. Portions of our themes (typically the .php files) that interact with Drupal are thus covered by the GPL and may be freely distributed
- The “look and feel” of our themes which includes files not dependent on Drupal (typically graphics and CSS) are not subject to the GPL and are the intellectual property of TopNotchThemes and licensed to you upon purchase via our website.
- You may not redistribute these files or use them for more than one production website
- We have no liability for and make no warranty for our themes
Great, plain, simple language. Go ahead and sell custom / premium / whatever themes day in and day out. The code bits of the PHP are a derivative work, and must be licensed under the GPL.
I've been looking for an excuse to dig into premium plugins as well (as a signpost towards thinking about such things in Drupal, especially as one digs into the many trademarked products / distributions that abound).
I think my friends at WordPress development shop BraveNewCode are doing excellent, pioneering work with WPTouch Pro. Read their Terms and Conditions for an example of how well done "premium" WordPress plugins / Drupal modules might be successful, all in accordance with the GPL.