MSDN Webcast on using XQuery in SQL Server 2005
Michael Rys (a program manager for XML technologies in SQL Server 2005) recently gave a webcast for MSDN where he covers some of the details of the new native XML data type. He gives details of basic usage, static typing, DML and indexing. Michael also goes into a good amount of detail on how to analyze query plans for XML and how to understand what indexes, etc. your query is using. Very worthwhile watching.