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

http://www-128.ibm.com/developerworks/library/specification/ws-secon/

The Web Services Secure Conversation Language (WS-SecureConversation) is built on top of the WS-Security and WS-Policy models to provide secure communication between services. WS-Security focuses on the message authentication model but not a security context, and thus is subject several forms of security attacks. This specification defines mechanisms for establishing and sharing security contexts, and deriving keys from security contexts, to enable a secure conversation.