Open-source WordPress Monitoring

There are several commercial sites (for example, [WebsiteDefender][1], [Sucuri][2], [VaultPress][3]) that have uptime and security monitoring for WordPress. I used WebsiteDefender while it was still in Beta for a project, but it now has a significant cost and the project I am working on wants to host the monitoring server alongside our Nagios install that is monitoring the rest of the network.

Does anyone know of open-source self-hostable client-server WordPress monitoring solutions? (Hooks into other monitoring solutions are probably good too.)