by Curtiss Grymala on WordPress.org
Allows anyone editing a published page or post to draft changes before those modifications go public.

The way the "Publish" metabox looks by default with this plugin active
This plugin adds a minor bit of workflow to the WordPress interface. When anyone edits a post or a page that has already been published, a few extra options will be available in the “Publish” metabox. Any time the appropriate option is chosen, the changes will be saved as a revision to the page or post, and the previous revision (the version that was already published) will remain published.
The person editing the page can choose from the following four options:
If the third or fourth option is selected, a box will appear asking the user to provide an email address (or multiple addresses separated by commas) to which to send the notification message. If that box is left empty, the plugin will attempt to retrieve the value of the “dpn_reviewers” option from the individual site. If that option doesn’t exist, the “dpn_reviewers” option will be retrieved from the network (if installed in a multisite environment). You can edit those options in the Settings -> Writing and Network Admin -> Settings -> Network Settings (multisite) screens within the administrative area. If neither of those options exist, the email address of the site’s admin will be used.