Im using fedora 17 x86_64, with driver 304.37 packed by rpmfusion. But this bug seems to be in ubuntu too.
I have a Dell Vostro 3500 laptop with an geforce 310m.
I needed to include "EnableBrightnessControl=1" to have lcd brightness control working. Contacting rpmfusion, they said that nvidia should fix this, enabling brightnesscontrol by default. So here Im.
I first followed this guide to fix this.
And here is the rpmfusion bug report