em_itunes_watch.rb

require 'ubygems'
require 'itunes_observer'
require 'eventmachine'

class EventMachine::ITunesWatch
  def initialize
    @observer= ITunesObserver.new
    @observer.on_pause do |result|
      paused(result)
    end

    @observer.on_play do |result|
      played(result)
    end

    @observer.on_stop do |result|
      stopped(result)
    end
  end

  def paused(result)
  end

  def played(result)
  end

  def stopped(result)
  end

  def start
    @timer = EventMachine::add_periodic_timer(1) do
      @observer.run(0)
    end
  end

  def stop
    @timer.cancel if @timer
  end
end

module Watcher
  def played(result)
    puts 'played'
  end

  def paused(result)
    puts 'paused'
  end

  def stopped(result)
    puts 'stopped'
  end
end

module EventMachine
  def self.watch_itunes(handler = nil, *args, &block)
    klass = klass_from_handler(EventMachine::ITunesWatch, handler, *args);
    c = klass.new(*args, &block)
    c.start
    c
  end
end

EM.run {
  EM.watch_itunes(Watcher)
}