A total of 568 hours of downtime at 13 well-known cloud services since 2007 had an economic impact of more than US$71.7 million dollars, said the International Working Group on Cloud Computing Resiliency (IWGCR).

The average unavailability of cloud services is 7.5 hours per year, amounting to an availability rate of 99.9 percent, according to the group's preliminary results. "It is extremely far from the expected reliability of mission critical system (99.999%). As a comparison, the service average unavailability for electricity in a modern capital is less than 15 minutes per year," the researchers noted in their paper.

Read the full article: Cloud Failures Amount to More than $70m Since 2007

Given many businesses have more than 1 hr of downtime every year and sometimes days, I'd say cloud is doing a better job than many places. Look at RIM and their failures. I know of other failures that were many hours or days. If anything, the report actually gives me more confidence in public clouds.