I've been playing with Ansible and recently had it installing Mosquitto.
It's a bit too trivial at the moment to turn into a fully fledged Ansible roll so I've just put a Gist here.
https://gist.github.com/justinatomatic/c2cf67a6c49bcdc8702e
It's only three tasks
# install mqtt broker
- name: add mosquitto key
apt_key: url=http://repo.mosquitto.org/debian/mosquitto-repo.gpg.key state=present
- name: add mosquitto repo
apt_repository: repo='deb http://repo.mosquitto.org/debian wheezy main' state=present update_cache=yes
- name: install mosquitto
apt: name=mosquitto state=present