Why heat? It makes the clouds rise!
An overview of the architecture is available. More details of the heat implementation can be found here. As the developers have only started development in March 2012, the architecture is in a rapid change.
The heat tool is a CLI which communicates with the heat-api to execute AWS CloudFormations APIs. End developers could also use the heat REST API directly.
The heat-api component provides a REST API that processes API requests by sending them to the heat-engine.
The heat engine connects to the heat-api over RPC to process API operations. The heat engine's main responsibility is to orchestrate the launching of templates and provide events back to the API consumer.
Web Site: http://www.heat-api.org
Mailing List: here
Open Issues: here
The developers use IRC on #heat on freenode for development discussion.
Status of implementation
March 16, 2012 - Code base started.
March 29, 2012 - Not quite launching a template yet.