The inkscape project has worked on a diff feature of django-cms, it's currently a separate app in our repository, but I'm brining it to django-cms project's attention to see if it's useful for other users.
See screenshots for examples. It follows the wikia diff form pattern and uses reversion with diff_match_patch to produce colour diff output.
Screenshots can be found on this closed bug report: https://github.com/divio/django-cms/issues/5556