Update: Machines up to MacBookAir 2,1 and MacBook Pro 5,5 are supported by maverick's default mbp_nvidia_bl. The X-Org Option "RegistryDwords" "EnableBrightnessControl=1" might be necessary on some machines. Please, always check by writing to /sys/class/backlight/mbp_backlight/brightness, because function keys involve too much subsystems to reason about bugs.
Update: Machines up to MacBookAir 2,1 and MacBook Pro 5,5 are supported by maverick's default mbp_nvidia_bl. The X-Org Option "RegistryDwords" "EnableBrightne ssControl= 1" might be necessary on some machines. Please, always check by writing to /sys/class/ backlight/ mbp_backlight/ brightness, because function keys involve too much subsystems to reason about bugs.