Comment 14 for bug 71204

This happens also on a Thinkpad R61, with Gutsy final release.

Additionally, writing to the proc node with commands like
echo level 7 > /proc/acpi/ibm/brightness
changes the value reported by the node, but it doesn't change the actual brightness.

The Fn+key combinations to change brightness work, but only when accessing a console via CTRL+ALT+Fn
See also bug #137972