So everyone's buzzing about the official announcement that Movable Type 4.0 is now available under the GPL license. For those who haven't been paying attention for the last couple of years, MT was the killer app for bloggers who wanted more control over their site and didn't have the time or the inclination to roll their own.

The release of Movable Type 3 alienated a lot of users by (gasp!) charging for multi-author blogs and installations with more than 3 installed blogs. It wasn't a big deal for most people, but it priced a lot of midrange hobbyists out of the MT world and set up the pins for Wordpress's ultimate domination of the universe. Movable Type remains a very strong multi-blog management system, and it has a great ecosystem of extensions. There's also a large pool of designers familiar with its purely tag-based templating language. The licensing hiccups with version 3, though, left a lot of individual users wondering if future penny-pinching would result in a squeeze for more licensing fees from smaller blogs.

The official release of MT4 under the GPL eliminates that fear, and opens up potential for adaptation and enhancement that's previously been off-limits. While MT's source code has always been available and hackable for its customers and users, it was "free as in beer," not "free as in speech." In other words, the modifications I made to enhance it couldn't be distributed to other users as "Enhanced Movable Type," nor could I distribute a copy of MT pre-configured with popular extensions.

While this isn't a big deal for many users, it's a big deal for interoperability with other GPL projects like Joomla! and Drupal. Those projects can now legally build bridges to the MT sourcecoude, integrating MT blogs into larger solutions like portal sites and intranets. It will also make the next version of Gutenberg, my Movable Type compatibility theme for Drupal, quite a bit easier to maintain. Why? I'll be able to legally include some of the MovableType base stylesheets in the Gutenberg download, making that theme usable from the moment it's installed, rather than pointing users to a separate download. It's a small step, but an important one, towards making multiple blogging systems compatible with each other for designers.

This principle goes both ways -- it's now possible for SixApart to make use of a large pool of GPL code that's in use in the wild. While I'm sure that wasn't their motivation, it's a nice door to have open. For companies like SixApart, where hosted services and corporate support contracts are the primary revenue stream, this approach is win-win. While it may not bring the legions of WordPress users back to the fold, it's a great moment for SixApart and Open Source software.