If you’re using vCloud in combination with vCenter Orchestrator, you should take a look at Workflow Runner provided by the vCO team. The workflow is included in the vCloud Director 5.1 blocking tasks and notification package. I think is the most valuable aspect of the workflow is that is extracts all the parameters from the vCloud blocking task (organization, vapp, user, etc) and passes them to any workflow that you specify. Not having to do this yourself saves a lot of time.
The vCO team has also released a Workflow Runner 1.5 to 5.1 compatibility chart that is helpful for converting your workflows after you’ve upgraded to the 5.1 vCloud plug-in. The guide can be found at vCloud Director 1.5 to 5.1 workflow compatibility guide.