I tried to run Fedora15 Live on a Thinkpad T420 (4180-A65). Everythink works fine except some minor problems. My kernel is 188.8.131.52-0.fc15
Brightness can not be adjusted. There is no /proc/acpi/ibm/brightness. So I can not write to it. When I press Fn+Home or Fn+End to adjust. It doesn't work. Maybe I need to modify xorg.conf. But the good news is that I can read/write from/to /sys/class/backlight/*/brightness. By this way, I can adjust brightness manually.
Volume can not be adjusted either. When dump /proc/acpi/ibm/volume. It reports: "level: unsupported". Do I need to pass some options to thinkpad_acpi module?
I can only use i915 for X window. Nvidia 4200 doesn't work by now.
Fan always run at fast speed. Maybe something is wrong.