This is the result from the latest Oneiric build.
ubuntu@ubuntu:~$ ls -hal /sys/class/backlight total 0 drwxr-xr-x 2 root root 0 2011-09-13 22:35 . drwxr-xr-x 49 root root 0 2011-09-13 22:35 .. lrwxrwxrwx 1 root root 0 2011-09-13 22:36 acpi_video0 -> ../../devices/pci0000:00/0000:00:02.0/backlight/acpi_video0 lrwxrwxrwx 1 root root 0 2011-09-13 22:36 intel_backlight -> ../../devices/pci0000:00/0000:00:02.0/drm/card0/card0-LVDS-1/intel_backlight
This is the result from the latest Oneiric build.
ubuntu@ubuntu:~$ ls -hal /sys/class/ backlight pci0000: 00/0000: 00:02.0/ backlight/ acpi_video0 pci0000: 00/0000: 00:02.0/ drm/card0/ card0-LVDS- 1/intel_ backlight
total 0
drwxr-xr-x 2 root root 0 2011-09-13 22:35 .
drwxr-xr-x 49 root root 0 2011-09-13 22:35 ..
lrwxrwxrwx 1 root root 0 2011-09-13 22:36 acpi_video0 -> ../../devices/
lrwxrwxrwx 1 root root 0 2011-09-13 22:36 intel_backlight -> ../../devices/