GNU Mailman's development is hosted on Launchpad and now Launchpad itself is officially and fully free software. While it was previously announced that two components would be held back, we (Canonical) changed our minds! Everything is licensed under the GNU Affero General Public License version 3.
This is significant for Mailman for two reasons. First, we are a GNU project so it's personally satisfying that our development is now hosted on free software and to know that now I work only on free and open software, both for pay and for not. Second, Launchpad's mailing lists are run by GNU Mailman so there are interesting integration issues involved. Some of the earliest design decisions about this integration strategy were driven by the need two and a half years ago, to keep a bright line between Mailman and Launchpad. That's gone now so the implementation of this can be reconsidered (although "if it works, don't fix it" applies here). I invite you to join us in the public forums to talk about Launchpad, Mailman, or both.