I use django-cms. I've just changed template for my page which ended with clearing my page (as expected). When I tried to restore old version (by using django reversion app that is suggested to use with django-cms) I realized this is impossible. I mean I have history of changes for my page but it looks like all reversion versions are broken (they pointed to lastly selected templates, all previous plugins inserted for placeholder are gone).
This is known problem in beta version: http://github.com/digi604/django-cms-2.0/issues/issue/510#issue/510/comment/301240