1. At a computer system in a computer networking environment including a plurality of computing systems, a method for providing an intermediary service configured to provide system functionality processing on received service requests and to determine which registered services are to be used to process the requests, the method comprising: an act of an intermediary service receiving registration information for one or more available services provided by a service provider, the registration information including information identifying functionality provided by the available services, the registration information being used to register the available services with the intermediary service; an act of the intermediary service receiving a service request from a client computer system identifying a function that is to be performed by at least one of the available services registered at the intermediary service; an act of the intermediary service determining which of the one or more registered available services is configured to provide the functionality requested by the client; an act of the intermediary service processing the received service request using one or more system functionality components, such that the service request is configured for service-specific processing provided by at least one of the registered available services; and an act of the intermediary service sending the processed service request to the registered service determined to be configured to provide the functionality requested by the client.