Auto adjust screen brightness data
See Amit Singh's Experimenting With Light On Apple Notebook Computers but note Apple do not provide official support for these methods:


  Please note that there are no Apple "APIs" to access the motion sensor or the ambient light sensor.


Amit's code examines the IOKit entry from AppleLMUController.

Also related to your question is How do you programmatically access the ambient light sensor on Mac OS X 10.5+?