hadoop.rb

require 'formula'

class Hadoop < Formula
  homepage 'http://hadoop.apache.org/common/'
  url 'http://www.sai.msu.su/apache/hadoop/common/hadoop-0.23.1/hadoop-0.23.1.tar.gz'

  def shim_script target
    <<-EOS.undent
    #!/bin/bash
    exec "#{libexec}/bin/#{target}" "$@"
    EOS
  end

  def install
    rm_f Dir["bin/*.bat"]
    libexec.install %w[bin lib libexec sbin share etc]
    #libexec.install Dir['*.jar']
    bin.mkpath
    Dir["#{libexec}/bin/*"].each do |b|
      n = Pathname.new(b).basename
      (bin+n).write shim_script(n)
    end

  end

end

BTW, you could change url and add md5