Comment 22 for bug 295251

It's a fault in how some of the Fn keys don't send the key release code, making the OS think that the key is being held down. I have submitted a patch to the kernel which fixes this issue, allowing the Fn keys (including brightness) to be used properly.

For those who want to see the patch:
http://bugzilla.kernel.org/show_bug.cgi?id=12021

To get the brightness to work, you also need to add the following scancode lines to /usr/share/hotkey-setup/samsung.hk
  scancodes e008 225
  scancodes e009 224

You should then find that the brightness works correctly. There is a scancode for the battery to make it work (but I don't have it to hand)

The wireless and other buttons are still a work-in-progress