http://dailyapps.net/2007/10/hack-at...-3-easy-steps/
It would be more like building a Ferarri using most of the performance related parts except for the body kits and interiors, since few Apples parts are solely manufactured by/for Apple, but the pretty packages that marketed as apple.
There won't be no Apple support, in case something happens as you should be aware of. No offense to Apple Advocates (or fanboys), I am merely suggesting the possibility.
In hindsight as apple market share climes they will look more attractive to write spyware on.