Apple released an update for the AppleTV this week that resolves the largest issue in using AppleTVs in a school. As covered here before, the AppleTV is a relatively cheap and powerful device that has many Interactive Whiteboard manufacturers scared. Previously, the only way to limit access to wirelessly project using the AirPlay feature was to set a password. Once the password was entered into a device, that device could "hijack" the screen from anywhere, as long as it was connected to the same network.
Now, an update is available which enables a simple fix. When "Onscreen passcode" is turned on, a 4 digit code will appear on the screen when attempting to AirPlay. Upon entering this code, the user will successfully connect. This forces the device to be in the same location as the screen, and eliminates headaches of the possibility of a projector being controlled by someone on the other side of campus.