Well i'm not sure which bean you are refering to....
Is it a View/Form Bean(Used at the View Layer to render the Supposed Page),Backing Bean(Used @ the Controller Side) or the Typical POJO's/Wrapper Classes/EJB's used at the MODEL(BIZ tier & DAO).
However,Please go through the below link which would give you a clear understanding of how to design an enterprise application with targeted MVC pattern.
http://java.sun.com/blueprints/guidelines/designing_enterprise_applications_2e/web-tier/web-tier5.html
http://www.javadude.com/articles/vaddmvc1/mvc1.htm
http://java.sun.com/developer/technicalArticles/javase/mvc/
Hope that might help :)
REGARDS,
RaHuL