An Introduction to the Web Services Architecture and Its Specifications

This new article on MSDN is a long, comprehensive overview of Web Services and their various specs.

Here is the article's summary:

Summary: This white paper provides an introduction to the Web services architecture. It describes the design principles underlying the architecture and foundational technologies for Web services. Features are described and linked to the specifications that formally define them. This paper also serves as a reference guide to all the specifications in the architecture. (45 printed pages)