http://forums.macrumors.com/archive/index.php/t-243504.html
"There are both backlit and non-backlit PB aluminum models.
The non-backlits are 12"
They keyboard brightness controls are not a preference in the system, but rather controlled by the F8, F9, and F10 keys. If you have them set to control Exposé instead, you have to hold down Function (fn) as well.
F8 turns on and off, F9 decreases brightness, and F10 increases."
Has anyone come up with a hack for the the 12" Aluminum laptops for a backlit keyboard? I take it the 12" keyboards lack the lighting element that the 15" and 17" keyboards have?
The lighting element for the 15" and 17" PowerBooks is actually integrated into the top case. Unfortunately, all those bands of fibre need to come together at one point so that they can be illuminated. Unfortunately, the bundle of fibre requires a decent amount of space that just isn't present in the 12" PowerBook. This is why there hasn't been a backlit keyboard model of the 12" PBG4's.
I once made a backlit keyboard for a 12" iBook G4 some years ago (used an iBook G3 keyboard, fibre from a 15" pbg4, and some custom wiring) that worked so so. Trouble is that there was no logic board controls for it (i.e. ambient light sensors) so it was on full time. The 12" PowerBook has no place for the ambient light sensors and lacks the controllers for a backlit keyboard.