Got this message from Amazon today:
This is a notification that your volume vol-XXXXXXXX experienced a failure due to multiple failures of
the underlying hardware components and was unable to be recovered. We recommend recovering from your
most recent snapshot.
We regret the loss and inconvenience.
Fortunately, this was on a mysql slave and it was easy to recover from a previous snapshot. Do you plan for failure of the systems you run on Amazon EC2?