In May 2008 my Macbook Pro, just out of warranty, began turning off at random. It would do this while on AC power as well as while running on the battery.
I took the computer to Apple for service, and after keeping it for several days until they could observe the problem, they sent it back to wherever such things go, and they repaired it.
Just this past week, in November 2008, the problem returned. The computer shut down twice yesterday, and three times today. This makes it difficult to work. I reset the power-management chip as the service tech recommended, but this did not help. (Today's failures were after the reset.)
Apple tells me that since the problem began to happen again after 90 days from the initial repair, this repair will cost me a few hundred dollars. I think that this is not acceptable because such a recurring issue is indicative of a design failure. I am happy with the computer in other ways, but this is just not reasonable.
The Appledefects site mentions here that the problem is widely known. It is my opinion that I should not continue to be charged for repairing a problem which is a result of a defective design. This computer was not inexpensive, and I expect better quality for my money than I have received.