My MacBook (white plastic) is just barely under warranty and my top case is beginning to chip on the edges. This has happened to me a few months ago and they replaced it at the Genius Bar but it took a few days. Tonight I tried to take my own top case out (just out of curiosity) and it was really really easy. Of course I could buy one of these top cases on eBay, but I'd rather get it for free through my warranty. Would they give me (or mail me) a new top case if I went to the store that I could put in myself? Probably not, but I thought it was worth asking.