I know that it's only possible through the aid of third party software (such as Rogue Amoeba's Airfoil), but is there a reason that iOS devices and Macs (or even a PC running iTunes) are unable to receive Airplay data? For instance, if I have an iPod touch on a dock, it would be really nice to be able to pass airplay to it from my laptop. I'm looking specifically at audio, although being able to push your iOS display to a Mac would be really cool too.