Is it possible for non-apple developers to integrate with AirPlay? Because that would be a really nice feature to have!
As a stop gap we have this in our FAQ:
Radio currently doesn't directly support Airplay.
However, if you'd really like to stream Radio via Airplay, here is a trick you can use:
Hold the Alt-key and click on the Volume icon in the menu bar, a menu will appear showing any available Airplay device. Select your Airplay device and all your sounds will play over Airplay.
(I know the key says "alt" too, but it's smaller type for a reason.)