I have already had the cracking thing repaired under warranty once. It has since done it again. Now that my version of the MacBook is no more, I'm going to haul it in on Nov. 28, 2010 (the last day of my AppleCare warranty) and kindly request they fix it again :-) Who knows, maybe I'll get comped an upgrade.
They'll replace it for you without complaint, but as an Apple Service Provider tech I can tell you, don't get your hopes up about the upgrade. Apple supplies its providers with parts for machines well after their warranties are all up; for a part like that, that's had problems all across the board, doubly so.
