October 13, 2009 — Matt Mullenweg gives an overview of the GPL and how it benefits WordPress, why WordPress is licensed under the GPL, how the GPL fosters innovation, affects themes and plugins, and creates value.
The directory of premium theme authors who support the GPL as mentioned in the interview is located here.
September 19, 2009 — Matt Mullenweg of Automattic answers questions from the WordPress community, including making money from open source products, migrating from WordPress.com to WordPress.org, the history of WordPress, the roles system in WordPress, core vs. plugins, blog comments, WordPress security, and more.
Video production by Joe Christensen of Blaze Streaming Media.
July 11, 2009 — A question and answer session from WordCamp Montreal with Matt Mullenweg. Questions were submitted by WordCamp attendees and also asked during the session, and cover such topics as tags on WordPress.com, the WordPress upgrade system, multilingual support in WordPress, and more.
July 2, 2009 — Automattic’s Jane Wells‘ presentation on Open Source community at WordCamp Denver 2009