This paper presents an architecture for service hosting on virtual clusters spanning multiple administrative domains that balances the requirements of application developers and resource provider system administrators. The presented architecture and implementation use virtual machines to simplify the deployment of externally-accessible persistent Web and Grid services while allowing resource provider system administrators to monitor hosted virtual machines and perform critical maintenance when necessary. This approach allows developers full control of their distributed resources, specifies a mechanism for resource provider monitoring and intervention, and reduces the barrier for hosting user-supplied virtual machines on shared resource provider cyberinfrastructure.