Q: just updated to macbook mountain lion and airplay isnt working ??

What model (year) is your MBP? AirPlay is only functional on 2011-2012 models.

Clinton

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).

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

About AirPlay Mirroring in OS X Mountain Lion

iTunes 10- About playing music with AirPlay

Troubleshooting AirPlay and AirPlay Mirroring

Using AirPlay

Airplay is only available on 2011 Mac models and later. You can still use Airparrot which is compatible with 2010 Mac models or earlier. You can get Airparrot at http://www.airparrot.com.

Hope this helps!

I just love being ignored, don't you?

I had a very frustrating experience with support  - here's a copy of my response to Apple:

After a frustrating 2 hour call on why airplay in Mountain Lion did not work properly  - see transcript of case # 356682008 - i was told to connect via ethernet cable to identify the issue. Ethernet Cable - in my household they went the way of dinosaurs as the one feature that made me upgrade to mountain lion was the ability to use airplay wirelessly - without having to connect the $60 Apple cable to my HDTV anymore. I do not even know the last time I had an ethernet cabe in my hands.

The fact that nowhere in your literature as of this morning requested an ethernet cable as part of the specification for use of the features of Mountain Lion basically equates to false advertising - either that or the MacBook Pro you sold me lack some of the functions that you were supposed to provide - I would like to know how are you going to fix this situation that does not require me to waste any more of my billable time with you.