Removing the 'Computers' menu item from the ATV 2 menu
You must be jailbroken to do this.  SSH into the ATV2 and then:


cd /Applications/AppleTV.app/
mkdir Appliances_Disabled
mv Appliances/Computers.frappliance Appliances_Disabled


Reboot.

You can move the Computers.frappliance directory back into /Applications/AppleTV.app/Appliances if you ever want to see it again.