[citation]The mac address is so simple to change that anyone with even basic computer skills can do it, its like having a ID where you can put in any data you want as long as it keeps the base format ...a nerd can do it, not a mere mortal.[/citation]
MAC addresses are not always point/click editable, apparently on a Mac they aren't permanent either (unless you use a software tool to change it on every boot). This still leaves it as a "serial number" of sorts, and on that vein there are MANY machine-readable indelible identifiers on components of a modern PC, such as the CPU and the hard drive. It would be practical for Apple to collect these during production and create a cross-reference database of components and users. Plus, who would buy a fenced Mac? I thought part of the Mac ownership culture was bragging about how many times you had to sell your blood plasma to be able to afford one?
This got me thinking, does Apple use any process to "identify" their customers who are setting up a new MobileMe or iTunes or other Apple-centric service and check them against a blacklist? It would make a ton of sense (at least until thieves cracked the numbering or checking process and loaded a malware-like tool to override it).