chunk.rb

class Array
  def chunk
    ret = []
    current = nil
    current_a = []
    self.each do |x|
      if x != current
        ret.push current_a
        current = x
        current_a = []
      end
      current_a.push x
    end
    ret.slice! 0 #A little bug in the logic makes this necessary
    ret
  end
end