To control my Backlight im using Julien Blache's pommed[1].

pommed is a daemon handling the hotkeys found on the Apple laptops, like the MacBook Pro, MacBook and PowerBook laptops. These hotkeys control, through pommed, the LCD backlight level, the audio volume, the keyboard backlight level (only on the MacBook Pro and the latest PowerBook) and the CD/DVD drive ejection. Additionally, pommed monitors the ambient light sensors found on the MacBook Pro and the latest PowerBook to automatically light up the keyboard backlight when the ambient light level gets too low.

1. http://alioth.debian.org/projects/pommed/

Marvin Stark <marv@der-marv.de>