Sitecore 8 has changed the way renderings on a page are stored on an item. A page’s full presentation can now be updated (hopefully through the Experience Editor) for an individual version…meaning those changes can go through workflow to be approved. It also means layout changes can be rolled back to previous versions easily.
Note: Screenshots and investigation for this post has been done using the Sitecore 8 Technical Preview handed to Sitecore MVPs. The final result may change for the initial release of Sitecore 8.