Railscasts Episode #177: Model Versioning

http://railscasts.com/episodes/177

Commands
  
  sudo rake gems:install
  script/generate vestal_versions_migration
  script/generate migration version_existing_pages
  rake db:migrate

script/console

  p = Page.all
  p.versions
  p.revert_to(7.minutes.ago)
  p.content
  p.revert_to(:last)