Synapse is not a puppet/chef like configuration management tool, it is used for live management & orchestration.

It's in fact much more similar to mcollective and salt, which both innovates from tools like cssh by using a messaging middleware instead of ssh to connect to the target hosts.

Ansible[1] is starting to look really nice. It's kind of a mix between puppet and fabric, handling configuration and orchestration in a single tool. If it didn't mean rewriting all my puppet configs, I'd probably be using it by now (though I've come close a couple times).

1. http://ansible.github.com/