The workflow module enables you to create arbitrary workflows in 
Drupal and associate them with node types.

Workflows are made up of workflow states.

Moving from one state to another is called a transition.

Only some roles can switch from some state to another.
The permission system is well thought-out: though complex,
workflow allows to see who can do what at a glance.

This allows managing content in more subtle ways than
published/not published.