We started the Drupal theme, Brambles, to learn about the Drupal content management system. Specifically, we aim to properly leverage its php-template theming system. Believe it or not, it's the theme we use on our site. :)

Currently the theme's status is what we'd like to call v0.25. It has begun its roots, and we have a working example in our site. It's still very rough around the edges and it works for us. Check out the Brambles Roadmap for an outline of our plans.

The theme is licensed under the GPL version 2. We'll release the sources to anyone who wants them now... but we're going to work toward Milestone 2 before we post a downloadable package.