I've been using a talking about Serverspec lately. Let me tell you about the surprises I found.
I've been involved in a Red Hat Satellite (version 5) project recently.
Do you want to set a default value for variables in CFEngine? Here are two methods. The first uses defaults promises. Defaults promises can be bit confusing and I've seen bugs in them in the past, so test carefully when using them. See the CFEngine reference for more details on defaults.
Here's a quick example of how to use mustache templates in CFEngine.