Apress has released three very interesting titles on Spring 2.5.
1. Spring Recipes: A Problem-Solution Approach
I read and reviewed this book for Javalobby, and gave it 5 stars for all the categories.
2. Pro Spring 2.5
I might start reading this soon..
3. Pro Java™ EE Spring Patterns: Best Practices and Design Strategies Implementing Java EE Patterns with the Spring Framework
I am reading this book currently, and didn't find anything new which I didn't otherwise know about the Java EE design patterns. Haven't tried working on the code samples either.
If you are using or planning to use Spring, than you definitely need 1 and either 2 or 3.