AirPlay Mirroring makes streaming easier on OS X Mountain Lion. If you have upgraded your Mac computer — iMac, MacBook Pro, Air — to OS X 10.8, then you can wirelessly stream Mac’s desktop to Apple TV.
Apple Products that can use Apple Mirroring:
There is a strict requirement of Apple TV 2nd generation. The older Apple TV will not support AirPlay Mirroring.
I have iMac, 2010 model, and I am frustrated to know AirPlay Mirroring won’t be available on my computer. With a decent processor and RAM, my iMac is powerful enough to welcome AirPlay feature, but nope — Apple decided to stop AirPlay Mirroring permanently. There are no workarounds at the moment.
Are you using older Macs that dates back to 2009 or 2008?