So i just got a new apple tv 3 (yay) and when i set everything up it looked as though airplay was working from itunes, but when i go to display preferences menu to see if i can mirror my display to the apple tv, that option does not exists. ( i am on 10.8) Ive seen numerous videos of this working and its just not for me.. Whats going on... 
I have an 2.4 i5 mbp
I have an 2.4 i5 mbp