Very recently announced, a version of Movable Type 4.0 will be open source:
The MTOS Project is a community and Six Apart driven project that will produce an open souce (sic) version of the Movable Type Publishing Platform that will form the core of all other Movable Type products.
This is, no doubt, in response to the fierce competition to the far superior WordPress and up-and-coming products such as Habari et. al. I used to run MT on this very blog, so the real question is: too little, too late? My mind immediately jumps to an article entitled Freedom 0 by Mark Pilgrim, which I’m sure caused countless of MT users to switch to WordPress.
That said, I’ve begun to actually miss the static pages that MT generated. For once, I’d like to see the file-server go down, rather than the database-server. WP-Cache just isn’t cutting it. There’s more on both the Open Source aspect and the new features.