Interesting Rackspace leaving post:

"Rackspace Cloud has had pretty atrocious uptime over the year there has been two major outages where half the internet broke. Everyone has their problems but the main issue is we see really bad node degradation all the time. We’ve had months where a node in our system went down every single week. Fortunately, we’ve always built in the proper redundancy to handle this. We know this will happen Amazon too from time to time but we feel more confident about Amazon’s ability to manage this since they also rely on AWS."

There was some statements from Amazon employees that Amazon isn't hosted on AWS.