Workflow lets you limit control of publshing rights to certain authors in your Movable Type installation, allowing other people on the system to act as editors and review entries before they're published. Administrators can control who has rights to any of these levels of permissions. Plus, authors can transfer ownership of a post to other authors and they'll be notified by email when the transfer happens.
The most remarkable thing about this release, which is supported by a free personal license and $250 commercial license, is that the Workflow plug-in can be extended with plug-ins.
I'm skeptical that third-party developers can be profitable creating add-ons to weblog software, even a product as popular as Movable Type. As the author of books on Radio UserLand and Movable Type, I'm finding it difficult when the pool of potential customers is limited to a single weblog tool, though I greatly enjoyed writing the books.
But I'd love to be proven wrong.