This is a CiviCRM extension to make it possible for a Nagios monitoring system to track the functioning of a CiviCRM site. Initially, services tracked are:
- whether CiviCRM is up-to-date
- how recently cron has run
- extensions that are out-of-date
- what the mailing backend is
- if a payment processor is set up
This won't help CiviCRM itself function, but it will help you track it alongside other systems that you may be using.