I can not see AIRPLAY Icon on My IMAC to mirror my new APPLETV 3rd gen my imac was bought from apple store in september 2011

About AirPlay and Airplay Mirroring

AirPlay Mirroring requires a second-generation Apple TV or later, and is supported on the following Mac models: iMac (Mid 2011 or newer), Mac mini (Mid 2011 or newer), MacBook Air (Mid 2011 or newer), and MacBook Pro (Early 2011 or newer). For non-qualifying Macs you can try using Air Parrot.

Several Apple Articles Regarding AirPlay

Apple TV (2nd and 3rd gen)- How to use AirPlay Mirroring

How to set up and configure AirPort Express for AirPlay and iTunes

iTunes- Troubleshooting AirPlay and AirPlay Mirroring

iTunes- Using AirPlay

Apple TV (2nd and 3rd gen)- Understanding AirPlay settings

About AirPlay Mirroring in OS X Mountain Lion

iTunes 10- About playing music with AirPlay

Troubleshooting AirPlay and AirPlay Mirroring

Using AirPlay

Thanks to the $15 Beamer, AirPlay streaming is still possible on Macs that do not support Airplay and mirroring.

Other solutions are the Air Parrot, StreamToMe, and AirServer.

Did you really manage to read all the links provided by Kappy and try all suggestions contained therein in 16 minutes. 😉

AirPlay requires OSX 10.8 or better.

Ooops, somehow that was deleted.

I am using my AppleTV on my 10.6.8 computer. I just updated my itunes account and the wee icon is now next to the play window.. works fine.

That is basic airplay, not mirroring.