i have that crack too on the arm rest
but i send it back to RMA.. 5 days settle...
they chg whole new top case..

reason of the crack is..
you close the lid too fast and too hard.. thn it will crack..
you must close it softly.. or can even put a cloth between it.. to prevent any future damage.

This post has been edited by danieljoey: Dec 5 2007, 10:55 PM