Hi Kais,
At the time of writing Getting started with Spring Framework book, the version of Spring available was 3.2.0 RC2. All the examples work on Spring 3.2.0 GA release, and the source code that you download from
http://code.google.com/p/getting-started-with-spring-framework/ make use of Spring 3.2.0 GA release and
not 3.2.0 RC2. If you want to run examples on 3.1 GA release, you need to explicitly include CGLIB dependency in your pom.xml file because in Spring 3.2.0 CGLIB classes are included inside the spring-core JAR file (this is also specified in the book).
regards
ashish