The coating everyone is referring to is the Anodized aluminum... on a hardness scale, it's about as hard as diamond, but is formed by a chemical process, so it can be stripped pretty easily.
Soaking the metal in oven cleaner is the easiest homemade method for this. After the anodizing is removed it will look really bad, but THEN, it can be buffed to a shine, or get it re-anodized or chromed...

I was contemplating getting my 12" re-anodized in red before I sold it (have a macbook 13 now...- call up a few local rim shops, most do in-house anodizing, but will need the parts stripped of all plastic first.

on the 12 and 15" powerbooks the lcd cover comes off after removing the screws at the base of lcd face, then working around the edge with a plastic stick. pop off the cover, then remove the AP antennas to get it the rest of the way off.

Powder coating would work- that's paint, but please don;t try to buff the surface unless you have enough service parts on hand to fix the mistake

Or if you want to do it cheap as you can you can try the Dupli-Color Metalcast paint.

http://www.duplicolor.com/products/metalcast.html

You can use the primer for it to ftill in then sand smooth then paint it.

That Metalcast paint looks so hokey though. I played with it back in my spray paint days, and I just wasnt impressed. So far, the mirrachrome is the closest I've seen to a really good mirror shine. At some point, I plan to order some of the mirrachrome, and spray a kandy orange over top of it in a light coat. I should end up with a mirror reflective kandy color. We'll see.

Oh, and while I knocked duplicolor's metalcast, I have to give them props for their sandable primer, and clearcoat, its not like shooting House of Kolor products, but they get the job done for sure.

The duplicolor looks rad as tinited clear coat in my opinion...  I've never tried it on reflective surfaces, but it can give some nice depth.  may be a nice combo with the mirrachrome since you need to clearcoat it anyways.  is the "Kandy orange" a specific coating? 

Anything's possible with the aluminum.  I wouldn't use a rattle can paint EVER because it'll probably diminish the value of whatever item you're using.  For the inexperienced folks, take the parts to a plating shop.  Ask them to polish the hell out of it. 

Exotic colored automotive paints like the chrome effects kind are entirely too expensive.  You'd be better off getting the aluminum chromed.  Aluminum is also expensive to chrome but at least it holds nicer than the overpriced paint would.