There are a number of threads around here detailing the struggles of laptop users with brightness controls (which are by and large absent when using the nouveau driver - but hey, I want to run the Nvidia drivers to get access to CUDA, that's the whole point of me insisting on Nvidia graphics). It shouldn't be so hard.
On my Sony Vaio VPCCW2DGX/B I can get a working brightness control file under
/sys/class/backlight/nvidia_backlight/brightness. I guess that a similar trick can be done on a variety of laptops.
Maybe it is possible to add some configuration options to a future version of the driver. In the spirit of the
Option "3DVisionUSBPath" "/sys/bus/usb/devices/1-1"
option, which takes a path as an argument, maybe we could see a
Option "BrightnessControlPath" "/sys/class/backlight/nvidia_backlight/brightness"
option, and perhaps another option where one can specify the range?