Amazon's execution with EC2 over the past few years has been excellent. If Amazon makes a Rails version of Beanstalk, Heroku should be worried as Beanstalk could take some market share from Heroku.
“We’re working with AWS to provide an Elastic Beanstalk Ruby on Rails container that leverages the optimized Engine Yard stack which has been battle-tested by thousands of high-growth companies.” John Dillon, CEO of Engine Yard
http://www.businesswire.com/news/home/20110119005591/en/Amaz...
Now, Amazon may start siphoning off python users that switched to rails just to use Heroku.