Installing OMD (Open Monitoring Distribution - http://omdistro.org) has never been easier. Just follow the steps for your linux distribution and your Nagios or Shinken is running in under 5 minutes.
Be careful with the snapshot repositories. They are for testing only and should not be used in production.
The OMD Repository has been merged with the Consol Labs Repository which contains OMD as well as other Opensource projects from Labs.