Erica Sadun created a hack for those who still use a Mac Mini or other Mac as a MediaCenter connected to TVs. She created a Mac Application called “AirPlayer” that can catch Airplay from iOS devices and output the video on the screen. For all intents, AirPlayer lets your Mac do what an AppleTV does naturally.
“By interacting with iOS devices the same way that Apple TV does and providing the same kinds of services and feedback, AirPlayer allows you to use your iDevice’s built in AirPlay support to send video to your Mac.”
You can download the alpha of the Macintosh Application AirPlayer here.