As someone once said, the good thing about standards is that there are so many to choose from!
As the clients and services become more mission critical and more sophisticated, a number of new standards are cropping up. Collectively, these are often called WS-* or Advanced Web Services. These services go by names such as WS-Security, WS-Trust, WS-Privacy, WS-Federation, WS-SecureConversation, and so on.
To learn more about these services, consult the Pocket This Decoder for WS-Alphabet Soup.