if you have an iMac and aren't aware or affected yet, there is a severe problem with the screens developing lines. it starts (of course) on the wrong side of the warranty, and has happened to thousands of iMac users. my big fat milky white block started about a week ago and from what i've read, this is only the beginning...
apple is freezing and erasing threads about this issue, so that may be an indication of where they stand... i hope not and that they issue a recall.
many have had the screens replaced, only to have the problem reappear...there is an online petition which one can sign. hopefully you are not part of this growing 'club'.
http://www.petitiononline.com/mod_perl/signed.cgi?maclines&1
i signed the petition as number 1,931 yesterday and today it is at 1,941! many had same problems with MBPs, MBs, and larger iMacs, and many have the same problem with multiple computers. worried about my new MBP.
while the majority seem to be in the serial # W86-W85 range, a quick scan also shows: QP7, QP6, YD5, W87, CK6, W80, W88, WH7, QP5, W84, W60, WB6, 3T6, CK5...

perhaps all from the same factory, or perhaps more #'s will start showing as the problem starts after a certain amount of time (1-2 years... or just after the warranty expires). it is not the screen as all replacements seem to catch the same 'disease'. some are reporting also logic board, hard drive and super drive failure. there is a class action suit filed at the start of January 09. it is extremely disappointing Apple is not acknowledging an obviously widespread hardware defect (and is actively freezing/deleting threads), but hopefully they are waiting to discover the exact cause of the problem so they can offer the proper recourse. a recall of a severely defective product seems to me the solution, as the quoted 'repair' price is more than half the price of the computer, and is so far ineffective in fixing the problem.
(though i am reminded of certain car companies not recalling known lemons until the lawsuits from fatalities exceeded the $ of a recall... i hope Apple has much more integrity!)