Distributed transactions in Spring, with and without XA is a JavaWorld presentation in which SpringSource's David Syer guides you through seven patterns for distributed transactions in Spring applications, three of them with XA and four without.

Java Transaction Design Strategies is a book available from InfoQ that provides a well-paced introduction to transactions in Java. It also includes side-by-side examples of how to configure and use transactions with both the Spring Framework and EJB3.