Brightness control doesn't work by default in Ubuntu 13.04.
Solution for 12.10 doesn't work, also as this

Any idea how to fix it?

Update:

After research I found how to change brightness manually. What need to do is to type in terminal:

echo 2000 | sudo tee /sys/class/backlight/intel_backlight/brightness

It will reduce brightness by half, but still would be good to find solution which will allow to use keyboard for changing brightness.

Update2:

Found solution, see below