AWS CloudFormation gives developers and systems administrators an easy way to create a collection of related AWS resources and provision them in an orderly and predictable fashion.
With CloudFormation, you can start and stop an entire environment with one operation.
It’s very similar to Microsoft Azure’s approach with their .cscfg and .csdef files which are an analogous XML model – you really could fairly call this feature “Amazon implements Azure on Amazon” (just as you could fairly call Elastic Beanstalk “Amazon implements Google App Engine on Amazon”.)
Amazon CloudFormation: Model Driven Automation For The Cloud
There is one nasty thing at the moment is that there is no support for Spot Instances in the CloudFormation 😦