django-reversion is an extension to the Django web framework that
provides comprehensive version control facilities:

- Roll back to any point in a model's history - an unlimited undo
  facility!
- Recover deleted models - never lose data again!
- Admin integration for maximum usability.
- Group related changes into revisions that can be rolled back in a
  single transaction.
- Automatically save a new version whenever your model changes using
  Django's flexible signalling framework.
- Automate your revision management with easy-to-use middleware.

django-reversion can be easily added to your existing Django project
with an absolute minimum of code changes.

WWW: http://pypi.python.org/pypi/django-reversion/