This is something I've been looking for in Moveable Type. David Raynes has created a Moveable Type plug-in called Workflow, that allows a Moveable Type editor to grant authoring privileges to authors to post drafts, which then can only be published by the editor. This will be great for those in education that seem to get very worried about teachers posting content to the web without it first being cleared by a principal or some other web gatekeeper. Of course they have no problem trusting these same teachers with a room full of 7 year olds, but for some reason the thought of them publishing content to the web gives them the willies.
I also see this as a nice tool to complement the writing process. Students can edit drafts, use the workflow process to gather feedback, and then when appropriate, a teacher or advisor can publish them to a site.
Workflow allows you to grant publishing permission to only the authors you choose (editors), while other authors (contributors) may only save entries as drafts. Once satisfied with their entries, contributors can transfer their entries to an editor who may then publish the entry to the blog.
Any author or editor in the system is notified by email when an entry is transferred to their ownership.