Binary package “radeontool” in ubuntu lucid

utility to control ATI Radeon backlight functions on laptops

 Radeontool is a small utility to control ATI Radeon based laptops' backlight
 and external output functions. It is also able to dump the contents of
 registers for debugging purposes.
 .
 WARNING: Radeontool code has not been completely audited and may contain bugs
 that could damage your hardware. Use at your own risk.