"Apple has determined that a very small percentage of hard drives that were used in MacBook systems, sold between approximately May 2006 and December 2007, may fail under certain conditions.
If your MacBook was purchased in the date range listed above and shows a flashing question mark on the screen, please take it to Apple or an Apple Authorized Service Provider and they will examine the hard drive to confirm if it is eligible for a replacement, free of charge, under this program.
Note: If your MacBook is not experiencing the symptom listed above, you do not have to contact Apple or any Apple Authorized Service Provider. As always, Apple recommends that you back up your data. Learn more.

Identifying Affected MacBook Systems

Symptom:
A flashing question mark appears on screen when the MacBook is turned on.

Affected MacBook models:
13-inch black and white MacBook models with the following processor speeds and hard drive capacities:

Processor speed - 1.83GHz, 2GHz, or 2.16GHz

Hard drive capacity - 60GB, 80GB, 100GB, 120GB, or 160GB

Next Steps:
If your MacBook exhibits the flashing question mark symptom and matches the affected model descriptions above, the hard drive needs to be examined. Please take your MacBook to the Apple representative most convenient for you:

Apple Authorized Service Provider - Find one here.

Apple Retail Store - Set up an appointment with a Genius."

It would have been good for them to more details (like brand/model, etc.) of the drives affected. (Another case where specifics like that are missing.)
It may not be related, but this rings a bell from few years ago, IIRC where a drive/data recovery vendor first brought up the story of high failure rates with some specific firmware/build Seagate notebook drives used in MacBooks and Minis. (Original stories were on 60GB/80GB Seagate ST96812AS/ST98823AS models with firmware revision 7.0.1.) There were several posts on that subject back then but here's one I found from the Nov 28, 2007 news page.

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