They would monitor consumption of their allocated units at the Org vDC level. Admin > Organization vDCs. They shouldn't need to monitor actual real time consumption. that's a job for the System Admins and IT staff of the provider.
To understand how the users would consume, please read the whitepaper on them: http://www.vmware.com/files/pdf/techpaper/vCloud_Director_Resource_Allocation-USLET.pdf
