We were getting ClassCastExceptions when subclassing a subclass of
GenericHibernateDAO. This change to the constructor will fix it:

public GenericHibernateDAO() {
    Class clazz = getClass();
    while (!(clazz.getGenericSuperclass() instanceof ParameterizedType)) {
        clazz = clazz.getSuperclass();
    }
    	
    persistentClass = (Class<T>) ((ParameterizedType)
clazz.getGenericSuperclass()).getActualTypeArguments()[0];
}