Here are some links to usage examples of Hibernate Validator / Bean Validation:

• Method Validation with Hibernate Validator 4.2
• Presentation on Bean Validation: Best practices for real life
• What's new in Hibernate Validator 4.1
• Getting started with JSR 303
• Bean Validation with JPA 1.0
• Using Groups
• Bean Validation with EclipseLink
• Using Bean Validation with Apache MyFaces 1.2
• JAXB plugin to generate Bean Validation Annotations
• JavaWorld article: Hibernate validation in a standalone implementation
• Screencast: Java EE 7: JAX-RS 2.0 and Bean Validation