Artur Bergman has a posted an interesting article over at O'Reilly Radar about Amazon EC2 and S3 disaster planning. My favorite part:
Perhaps I used the wrong acronym when I used SLA. People have a conception that SLA is something heavy handed that rarely is useful. Now I agree that most SLAs I have ever seen are completely useless, but they do give you an idea how serious the service provider takes your custom. The quote from the T&C is effectively an SLA, one that promises absolutely nothing.
Worth a read if you're responsible for online operations.