For Rails 3, ActiveSupport::Callbacks gives you the necessary control. I was just facing the same challenge in a data integration scenario where normally-desirable-callbacks needed to be brushed aside. You can reset_callbacks en-masse, or use skip_callback to disable judiciously, like this:
Vote.skip_callback(:save, :after, :add_points_to_user)
..after which you can operate on Vote instances with :add_points_to_user inhibited