How can you replicate Hibernate's saveOrUpdate in JPA?

In JPA, is there any way you can replicate Hibernate's saveOrUpdate behavior,

saveOrUpdate

public void saveOrUpdate(Object object)
                  throws HibernateException

    Either save(Object) or update(Object) the given instance, depending upon resolution of the unsaved-value checks (see the manual for discussion of unsaved-value checking).

    This operation cascades to associated instances if the association is mapped with cascade="save-update".

    Parameters:
        object - a transient or detached instance containing new or updated state 
    Throws:
        HibernateException
    See Also:
        save(Object), update(Object)

which essentially checks to see if the object already exists in the database and either updates that object as need be or saves a new instance of the object.

JPA transcationless reads are nice, but I am really missing this method from Hibernate. How do experienced JPA developers handle this?