Update:  We just released VMware cartridge 5.6.4.3 and this is official release to support virtual center 5.1.  Please this this link for more details information. [URL]  Regards -Lee
Just in case you missed this form your email  [URL]       vFoglight 6.7 and Foglight Cartridge for VMware (all versions) have a known issue with vSphere 5.1 environments where the products fail to collect data. How does this affect vFoglight 6.7 and Foglight Cartridge for VMware? Collecting data from vSphere 5.1 results in an Invalid Argument exception associated with the Relationship and Hierarchy collection in the VMware Agent that results in data not appearing in the vFoglight / Foglight Management server. Agent log contains below error messages:2012-09-14 14:10:18.422 ECHO ERROR [Quartz-1226] com.quest.agent.esx.task.RelationsTask - Error during execution: ERROR: null com.vmware.vim25.InvalidArgument2012-09-14 14:10:18.422 ECHO FATAL [Quartz-1226]com.quest.agent.esx.task.RelationsTask - An unexpected error occurred while connecting to the VirtualCenter. Please review your agent configuration to ensure proper connection information has been entered. Currently, there is no workaround for environments that have already been upgrade to vSphere 5.1. A product defect has been filed as VM-3207 and R&D is working on a permanent fix.  Updates will be posted on the Support Portal in the knowledge base article SOL97413. Once a permanent fix is released a follow up notification will be sent.
Virtual Center 5.1 support