My solution (pastied too: http://pastie.org/263518):

module Kernel
  alias :require_orig :require

  def require mod
    if success = require_orig(mod)
      file = $".last

      $:.each do |dir|
        path = "#{dir}/#{file}"
        if File.readable?(path)
          puts "require #{mod} => #{path}"
          break
        end
      end
    end

    success
  end
end

if __FILE__ == $0
  ARGV.each { |mod| require mod }
end


-- 
Jesse Merriman