Ari Paparo set out to deploy a weblog and discovered he needed version control and workflow [via Loïc Le Meur]. Given the problem, I doubt that MovableType plugins are the answer. He needs to move up the content management system food chain.
Weblog software focuses on presentation and authoring. If authors want to enforce version control and workflow upon themselves, then plugins will be fine. But if corporate wants to enforce it upon them, then plugins will just be another finger into the dike. Weblogs are built for easy access and manipulation of content. Try to wall it in, and it’s going to leak out.
The content lifecycle can be quite complex. Who can see what content in which state? How does content move from state to state? Who can do what when (easy to delete versions before release, but next to impossible after)? It’s easier to modify the authoring and presentation of an appropriate CMS than to add control after the fact.