1. A method for storage and retrieval of directory data in a directory system running on at least one processor having access to at least one data storage device and at least one communications network with interfaces to at least one application running on other processors having need of directory system services, said method comprising: running plural intelligent directory service modules as a part of said directory system, said intelligent directory service modules comprising (a) an identity management module, (b) a presence management module, and (c) a messaging management module; storing data objects used by the directory service modules in respectively corresponding different organized logical segments of memory, each segment containing object attribute data needed by the corresponding directory service module to perform its intelligent service in response to an incoming request; receiving directory service requests from said application(s) running on said other processors, said requests including an identification of the type of requested directory service comprising (a) identity service, (b) presence service, and (c) messaging service; directing received directory service requests to the directory service module respectively corresponding to the identified type of requested directory service; and returning responses to incoming requests based on the outputs of at least one intelligent directory service module without requiring access of other object attribute data separately stored for another of the intelligent directory service modules.