Like many other uses, my MB has developed cracks along the right palm rest from the screen standoffs. I also found a hairline crack along the fan vent on the bottom, among other issues (some keyboard keys miss, mechanical problem, and headphone jack does not retain headphone). I've had it since February, palm rest cracks appeared around May, but didn't get a chance to take it into a store until now. They agreed to replace the cracked palmrest area (which also replaces the keyboard, fixing the keyboard issues). The specialist at the genius bar said that the bottom case cracks (near the vents) are considered 'accidental' and would cost $420 to repair. I've never dropped it, always stored in a padded sleeve or bag purchased from the Apple store (timbuk2 commute and incase sleeve). I think it's a design flaw -- thin brittle plastic + cyclical loading = cracking. The specialist agreed it likely wasn't from setting down too hard, but claimed that the repair center would not repair it free-of-charge under any circumstances. This is after a few years of staying away from Apple products because of an ibook i had to send for repair a few times (first the wireless was DOA, not just the card but antenna was broken, logic board failure, white spots on screen). I switched back to Apple products a year ago - iMac, iphone (original and 3g), ipod 80GB. But I'm still very disappointed by the durability of the MB's... in between I owned a cheap Dell, the screen went bad after a couple years but never had any case durability issues... just need to vent my frustration. Now I need to decide if I should just sell the MB and get an aluminum MB, or keep it. I really don't want to have to pay $300 to extend Applecare just to fix the palm rest issues every time it starts to crack.