This morning I performed the following relevant updates:
- linux-image-2.6.27-11-generic (2.6.27-11.22) to 2.6.27-11.23
- system76-driver (2.2.7) to 2.3.0
The GNOME Power Manager Brightness Applet now shows a red circle-and-slash, with flyover text of "Cannot get laptop panel brightness". Additionally, the Fn+F8 and Fn+F9 keys no longer adjust the backlight.
What should I do to regain this functionality? Are there any logs you want to see?