The receivers will have two different iOS apps included with the purchase. iControlAV2 will allow the user to remote control a home theater setup from an iOS device, and Air Jam will create play lists from up to four different iOS devices.
The biggest part of the news, though, is that the high end models will include direct support for AirPlay. This feature allows you to connect to the AC receiver wirelessly with your iOS device, and stream music directly to your home theater setup. While AirPlay obviously already exists, there isn't a wide range of home theater devices already using it. AirPlay will only be available on the higher end Pioneer receiver, but that's a step in the right direction.