15 Months and still going strong here.
Have replaced the topcase for the cracking issue (didn't know at the time that was covered under warranty), but the new one is holding up quite well. No staining to speak of, and the first one had become quite stained. Some dents from use, and one recent one where my friend tossed me his busted ipod... hit the top of my screen... nice little dent there now, jerk
Mine has been dropped, tossed, flipped, scratched, pounded upon, left in the cold, left in the heat, opened and examined more times than I can count, and generally not handled like glass. It is holding up exceptionally well, and I expect it to continue to do so. At some point I will replace the hard drive and add more RAM, but other than that, I don't expect that I will have to do much to keep this thing is excellent working order.
I do feel for Billy Bob's plight, but I serviced a G4 iBook recently... the polycarb that makes up the shell is much more brittle than on the MacBook, and was cracked in quite a few places. The keyboard had had the letters rubbed off from use (I have slightly acidic skin and my keys are still great) and in general it did not look to be in great shape. And this was a machine that basically went from desk to couch and back again, nowhere near the abuse that I have shown mine. I think his was the exception, and not the rule.