Yes Alienware does paint their systems. They say they are "Professionally painted." I have spray painted many of my systems. When I couldn't find a black case to suit my needs that had a door to cover the drive bays I got a very nice white case with a door and spray painted it black. It turned out very nice and still looks good after three years. I also have a case made out of wood. Yes it probably is a fire hazard but damn it looks good.
Next system I want to build I want to suspend every component from high-test fishing line inside a large plexy glass box that is also hanging from the ceiling. =) I think that we should not be confined to the simple imaginations of computer case companies and brake out of the simple rectangle box. We spend a very long time customizing our digital desktop why not spend a little time on the outside.