I think workflow and workflow fields are the best permissions modules for drupal. You can do anything down to cck field level and taxonomy term level.
There's just one thing: you cannot control comments on the nodes. Wouldn't it be great to have an option to «view all comments» and «post new comments» for each workflow state?
Comments
Comment #1
infojunkieYour suggestion makes me think that any permission on node types that use workflows could be dependent on the workflow state. I'll explore how to achieve this.