I'd prefer that users not need to know these details, at least not right up front.

PuppetServer is the brains of the operation. It's a JVM-based (Clojure + JRuby) application that:

PuppetServer runs inside a Jetty web server and uses JRuby to execute Puppet's Ruby-based compiler.

The way that it's presented right at the beginning make it seem like it's one of the most important details instead of being implementation details.