Most useful book on web services security (so far)

The most useful book on Web Services Security that I've read so far is:

Web Service Security - Scenarios, Patterns, and Implementation Guidance for Web Services Enhancements (WSE) 3.0

It takes a patterns-based approach to security, with architecture, design and implementation patterns. As you could expected from a Microsoft book, all the implementation details are for Dot Net's WSE 3.0.