I've had several customers who didn't like the idea that they couldn't really preview their article before publishing it. I have to admit, this always made me a little uncomfortable since the article editing environment isn't quite the same as the official live article. I know there are some nice tools in Drupal for doing this but I'd never encountered anything for Joomla but in all fairness, I'd never really looked.
So I decided to look for a solution that would allow a Joomla administrator to create an article and preview it on the site before it was published for all the world to see.
It turns out that there is really only one established solution that meets this requirement. Coincidentally, it also integrates version control so you can track previous versions of articles between edits.
Real Preview for Joomla
http://extensions.joomla.org/extensions/authoring-a-content/article-preview/17817
It's a commercial product that sells for about $35 per year membership. Of course it's GPL, so as long as you don't need updates, you won't have to buy it too frequently.
If you use K2, you need to buy a K2 specific version and of course if you have some sites that use K2 and some that use the standard Joomla content component, you'll have to buy both versions.
I haven't had a chance to try this extension out yet, but the reviews are generally positive.