If you enjoyed streaming from your iphone 4s siri to the apple tv 2 in headless mode (where the apple tv is connected to just an audio device without the hdmi cable), and if you had updated to ver of apple tv of 4.2.2, you would have been disappointed as that breaks the headless mode.
Now with the new update, of apple tv ver 4.3.3, the headless mode works once more! Now you can continue to use your iphone to be a dj and stream audio wirelessly to your audio devices most commonly using a receiver. I use a Yamaha reciever.
Now have fun streaming from your iphone devices, Ipads and even pc and macs to your audio devices using the apple TV.