One problem I noticed with the HibernateSessionConversationFilter was
that when redeploying my application, the network connection to the
database was not released. I fixed this by implementing destroy() like this:

public void destroy()
{
    try
    {
        if (sessionFactory != null)
        {
            Session session = sessionFactory.getCurrentSession();
            if (session.isOpen()) session.close();
            sessionFactory.close();
        }
    }
    catch (HibernateException e)
    {
        logger.error("Failed to close session in destroy()", e);
    }
}

I'm not sure if this code is perfect, but it works for me. The resources
are now properly released when I redeploy the application.