Amazon EC2 is now out of Beta after two year and now gets an SLA.

Service Commitments and Service Credits

If the Annual Uptime Percentage for a customer drops below 99.95% for the Service Year, that customer is eligible to receive a Service Credit equal to 10% of their bill for the Eligible Credit Period. To file a claim, a customer does not have to have wait 365 days from the day they started using the service or 365 days from their last successful claim. A customer can file a claim any time their Annual Uptime Percentage over the trailing 365 days drops below 99.95%.