This video demonstrates how a user can update a piece of published content, and send those updates through the revision process, without affecting the published version of that content.
Updating published content
This is where Workbench really shines! Logged in as "Author", I'm going to view the article. We see that the most recent revision is the published version. Let's say that I need to update the article after it was published. I can simply click the "New Draft" tab to make my updates.
Once I'm done editing the content, I can change the moderation state to "Needs Review" and save the article. You'll notice that I now have a new tab. I have: "View published", "View draft" and "Edit draft".
Let's take a look at the "Moderate" tab now that we've changed the article. Here, you can see that the previous revision is the published revision, and that the current revision needs review. I'm going to make one more change before we publish the updated article.
Once that's done, I'll head back to the "Moderate" tab, and you can see that the published revision will stay published while new revisions can be created and updated as needed. Now, I'll login as "Publisher" one more time and publish the changes.
Publishing the changes
Logged in as "Publisher" I'll go to the "My Workbench" dashboard and click the "Needs Review" tab. (There is currently a glitch in the workflow here. It's not showing the title of the article. This has already been reported, and you can get more info and follow updates on this issue at http://drupal.org/node/1245590.) Since I know which article it is, I'm going to go back to the dashboard and view it from the "All Recent Content" section. I can publish the draft from either the "View draft" tab, or the "Moderate" tab. I'll change the status to "Published" and click "Apply". Now, the most recent revision is the published revision.