# File lib/jekyll/site.rb, line 193
    def post_attr_hash(post_attr)
      # Build a hash map based on the specified post attribute ( post attr => array of posts )
      # then sort each array in reverse order
      hash = Hash.new { |hash, key| hash[key] = Array.new }
      self.posts.each { |p| p.send(post_attr.to_sym).each { |t| hash[t] << p } }
      hash.values.map { |sortme| sortme.sort! { |a, b| b <=> a} }
      return hash
    end