1. A service system comprising a service processing means and an interface for interfacing with a presence server for in turn interfacing with instant messaging clients, wherein: the service processing means comprises means for controlling interfacing with an instant messaging client to provide an interactive service according to an application and involving routing of multimedia content to the client; the system is modal, dynamically interacting with a client to provide a desired service in a current mode, and a mode of a service comprises a state of an application and an associated group of allowed user interactions; the processing means comprises a service core and a mode database manager for maintaining a persistent record of the mode of a service; and the service core interfaces with the mode database manager to allow a mode to persist through at least two instant messaging sessions of a particular client involving interaction.