I acquired my Dual 450 GbE from a friend who originally got it from someone who worked at Apple. I was told that Apple had built the machine as a prototype. I noticed on the back where they usually list the configuration, was blank, but this in and of itself was not proof of my Mac's unique origins. However, while installing an Airport card yesterday, I noticed a sticker on the inside of the machine. I'm paraphrasing here because I'm not at the machine, but it basically said "This machine is not for sale or resale because it has not been evaluated by the FCC". This may be commonplace, but I thought it was kind of intersting.