No brightness control with NVidia GeForce GTX 460M

Sun Apr 17 14:49:45 UTC 2011

I have a Asus G73SW-BST6, with a  Nvidia GeForce GTX 460M graphics
card. Setting the LCD brightness with Gnome doesn't really do
anything, although I can see the brightness values change in
/sys/class/backlight/acpi_video1/brightness. I've tried changing the
value manually, with similar lack of effect.

How can I adjust the LCD monitor brightness with this system?