Rogue Amoeba’s AirFoil has taken the step into the big league by now adding native AirPlay streaming to their AirFoil Speakers Touch 3 app through an in-app purchase, providing you with the ability to stream to pretty much any iOS device.
AirFoil started off being a way to stream non-iTunes audio to Airport Express mini-router before the first app was released allowing you to stream audio from your Mac to your iOS device. Now you can stream audio not only from your Mac but also from your iPad with native AirPlay, allowing you to have one of your iOS devices connected to your non-Airplay enabled sound system and stream audio to it from your other devices.
Always nice to see options for making existing systems AirPlay friendly. The AirFoil Speaker Touch app is available from the iTunes App Store for free, but the in-app purchase for native AirPlay costs £1.99.