After installing Fedora 15, and enjoying playing with Gnome 3, I was confronted by a disk warning at the bottom of the screen. After opening Disk-Utility it looked like my OCZ Vertex 2 120GB SSD was dying. However after some research, churning through the internet with Google riding shotgun with me, I discovered that the S.M.A.R.T. system on disk drives is not very smart at all!
Every manufacturer appears to have their own opinion on how it should work.
It reminds me of my friend Andy's favourite saying "You have to love standards in the IT world, after all there are so many to choose from that you can always find one that suits your purpose"
An article by Google (who possibly have more "vanilla" disk drives in use than any other one organisation) indicated that 56% of their drive failures were not predicted by monitoring the S.M.A.R.T. counters. http://labs.google.com/papers/disk_failures.pdf

I also discovered that in the Disk-Utility program there is a lovely little tick box available (that I missed the first half dozen times) that allows you to tell it to stop popping up warning messages for a particular drive. A wonderful option if it is annoying you, and like me, you believe it is getting the prediction wrong. (but maybe update that month old backup anyway, just in case)

Have a read of this http://forums.fedoraforum.org/showthread.php?p=1494778 forum page paying particular attention to the post by stevea. It is third up from the bottom, and explains a great deal about the subject.