vCloud Director 5.5.3 released yesterday, which can connect to vSphere 6.0. There are a number of issues that are linked to this interop (http://kb.vmware.com/kb/2108913/).
The vCloud Director 5.6 line does not support vSphere 6.0 at this time. As with any forward looking statements, like release dates and features, it is best to talk to your VMware contacts (e.g. account team) to see if you can discuss this with the appropriate people in VMware for guidance.