gistfile1.txt

require 'nokogiri'

module Nokogiri
  module XML
    class Node
      BLANK = /^[ \n]*$/

      # Comparing with other node
      # - same name
      # - same attributes
      # - same namespaces
      # - order doesn't matter
      # - recursively through all children
      # This will allow to compare two documents.
      def =~(other)
        match_nodes(other) && other.match_nodes(self)
      end

      def match_nodes(other)
        self.root.traverse do |elem|
          xpath_without_index = elem.path.sub(/\[[0-9]+\]/,'')
          other_nodes = other.xpath(xpath_without_index)
          return false if other_nodes.empty?
          # just compare highest level
          same_element = elem.element? && elem.match_element(other_nodes)
          same_text = elem.text? && elem.match_text(other_nodes)
          return false unless same_element || same_text
        end
        true
      end

      def match_element(other_nodes)
        other_nodes.any? do |node|
          namespace == node.namespace and
          name == node.name and
          match_attributes(node)
        end
      end

      # if both are blank, the number of spaces doesn't matter
      def match_text(other_nodes)
        other_nodes.first.text == text || ((other_nodes.first.text =~ BLANK && text =~ BLANK) == 0)
      end

      private
      # the compared node has same attributes as self
      def match_attributes(other)
        attributes.inject(true) do |memo,attr|
          memo && other.attributes.include?(attr[0]) &&
          other.attributes[attr[0]].name == attr[1].name &&
          other.attributes[attr[0]].value == attr[1].value
        end
      end

    end
  end
end

Approved but also improved: http://gist.github.com/451544 ;-)