Hyperic is application monitoring and performance management for virtual, physical, and cloud infrastructures. Auto-discover resources of 75+ technologies, including vSphere, and collect availability, performance, utilization, and throughput metrics.
Osmius: The Open Source Monitoring Tool is C++ and Java. Monitor "everything" connected to a network with incredible performance. Create and integrate Business Services, SLAs and ITIL processes such as availability management and capacity planning.