script/plugin install http://arperftoolkit.rubyforge.org/svn/trunk/conditional_page_cache

At the top of the controller, indicate which actions you wish to cache with conditionally_cache.

class MyController < Application

  conditionally_cache :action_one, :action_two

  def cache_page?(current_action_name)
    @user.demo?
  end

  def cache_action?(action_name)
    !@user.admin?
  end

end

To use page caching, add a method cache_page?(current_action_name) on the controller. The page will be cached if this method returns true.

Similarly, return true from method cache_action?(current_action_name) when you want to action cache the page. This method is the same as the one used by the action caching plugin which works great along with this one.