AWS CloudFormation Introduces YAML Template Support and Cross Stack References

You can now create YAML-formatted templates to describe your AWS resources and properties in AWS CloudFormation. Now, you have the option to use either YAML-formatted templates or JSON-formatted templates to model and describe your AWS infrastructure. YAML-formatted CloudFormation templates follow the same anatomy as existing JSON-formatted templates and support all the same features.
Quelle: aws.amazon.com