Well I help run an engraving business. This was done on a 35 watt laser engraver using CorelDraw X4. Our maximum engraving area is 12" x 24". The nice thing about the higher end Mac laptops is that their cover is made of aluminum which is a laser engravable material. I'm not sure how plastic covers would work...we can engrave plastic but usually it's a special type of laserable plastic. I can engrave on acrylic as well but I'm limited in the size of acrylic (12x24 max). I could probably take orders but laptops (or at least the cover if it can be taken off) would have to be shipped back & forth...that's the only problem...not to mention it's a little nerve racking engraving someone else's laptop. I can't always guarantee that things will come out ok, but usually they do.
I've also engraved ipods, you can see one here: