Keith Ballinger reveals why he's been busy lately - Bill Gates demos interoperable web services between Microsoft and IBM with an application that:

"links automotive parts suppliers, manufacturers and dealers via Web services that use new specifications to ensure security, reliable messaging, and transaction support." here

MSDN seems to have an excellent article that describes the application used in the demo (and more on the practical implementation of SOAs) titled Secure, Reliable, Transacted Web Services: Architecture and Composition. Omri Gazitts has more about the demonstration. 

Reliable messaging and transaction support are obvious features not covered by the current WSE 2.0 implementation.  I think reliable messaging is particularly important.  For example, the project I'm working with at the moment uses web services to poll a database to see when changes occur.  Reliable messaging would allow the web service to notify the client via a message when new data was available.