Joomla 3.2 is just around the corner, with the RC (Release Candidate) version released last week. One of the major things in Joomla 3.2 is content versioning. This means you can roll back to older versions of an article. You also have functions like compare, so you can see what has changed between different versions of your article.
Check out the video, where Mark Dexter explains how content versioning in Joomla 3.2 works in detail.