I've installed Fedora 14 on my notebook Samsubg R510 and found that I can't change LCD backlight using Fn+Up/Down. xbacklight doesn't work too. Fortunately
setpci -s 00:02.0 F4.B=hex_value
works. In /var/log/dmesg I see
[ 0.121535] [Firmware Bug]: ACPI: ACPI brightness control misses _BQC function
I tried to upgrade BIOS but it didn't help. I see same behavior with newest available BIOS.