Lust: PLP have said on twitter in reply to a question on data useage for a game on ipad that it runs at 3000kbs. 2.5 gb per game. They said iPhone runs much lower but couldn't confirm numbers.
There is not one set bitrate for either the iPad or iPhone. It uses the adaptive streaming like if you were on "best available" on your computer.
Just AirPlayed to the Apple TV from my iPhone 5. Started off on a low bitrate ~800kbps, settled on what i think was 1600, then just before I had to stop cause mum wanted to watch deal or no deal I'm pretty sure it went up to 3000 as I could hear a difference in the audio.