action_view_ext2.rb

module ActionView
  module Helpers
    module FormTagHelper
      alias_method :original_submit_tag, :submit_tag
      def submit_tag(value=nil, options={})
        options[:disable_with] = options[:disable_with] == '' ? nil : 'Sending...'
        original_submit_tag value, options
      end
    end
  end
end