I noticed my MBA keyboard lights wont work after updating to OS 10.8. Pressing the f5 and f6 buttons show the keyboard lights are disabled. Is anyone else having this issue?
It's always worked like this -- there is an ambient light sensor next to the camera on your Mac and if there is sufficient lighting in the room you are in the keyboard lights will not turn on.
I don't know if anyone is aware, but on new the OSX if you're low on battery your keyboard light will not work. Once you're plugged in or have enough battery power, it'll work.