Please vote for WS-Discovery if this is relevant to your enterprise web services

http://msdn.microsoft.com/library/en-us/dnglobspec/html/WS-Discovery.pdf

This specification defines a multicast discovery protocol to locate services. By default, probes are sent to a multicast group, and target services that match return a response directly to the requester. To scale to a large number of endpoints, the protocol defines the multicast suppression behavior if a discovery proxy is available on the network. To minimize the need for polling, target services that wish to be discovered send an announcement when they join and leave the network.