Thanks for the replies.
"On an X120 here (05CX BIOS)"
On SAMSUNG support site, the last available BIOS for the X120 series is 06CX.Its issue date is not mentioned, nor are known the differences from 05CX to 06CX, but the file seems available.
It's up to you to choose if you want to make the change and see what happens...or not.
Oh! Indeed, I'm glad you mentioned it so that I can rant
I'm currently having a heated debate with Samsung support about the virtues of DOS-based updaters. The 06CX updater doesn't work in Windows 7 - I'm pretty confident of this because i) 05CX worked for me ii) Support claimed 06CX worked on Vista iii) 06CX doesn't even unzip all the files on Windows 7 (compared to a virtual XP). I also suspect Samsung added 64-bit support in the 06CX updater - they flatly deny supporting 64-bit of course, but there are files whose names sound 64-bitty, and also it's twice the size.
Try to add the option "acpi_backlight=vendor" to your GRUB kernel command line.
That didn't work for me alone, but "nomodeset acpi_backlight=vendor" seems to do it.
nomodeset is a bit backward I suppose but having no control over the backlight is barmy!
I switched to Lucid Alpha 3 also, so I can't be sure your bindings would now work. Note that I know I tried acpi_backlight=vendor alone on Karmic, I didn't find out about using nomodeset until just now.