It is wonderful to note that you recognize and share our passion re: the provisioning, management and life cycle of virtualized infrastructure! Addressing these challenging problems is what keeps us going!
At the risk of pointing out something that you/your readers might be aware of already, VMLogix LabManager is a virtual lab automation solution that addresses the same problems that you note. Our product supports advanced levels of automation (to drive self-service IT on the provisioning front) and mature support for centralized virtual infrastructure management (across leading hypervisors from Citrix, Microsoft and VMware). The product enables user/team collaboration, VM config libraries, resource reclamation, resource audit trails and so on.