This was simple....

<rich:pickList value="#{event.sponsorDetails.sponsors}"> 
     <s:selectItems value="#{availableUsers}" var="eachUser" label="#{eachUser.surname} , #{eachUser.firstname}"/>
     <s:convertEntity/>
</rich:pickList>

Or so I thought...

    @Out(value="availableUsers",required=true)
    private List<User> availableUsers = new ArrayList<User>();

     
        /* (non-Javadoc)
      * @see nz.co.selwynequestriancentre.action.eventsManagement.EventsManagementController#findUsers()
      */
     @Factory("availableUsers")
     @TransactionAttribute(TransactionAttributeType.NOT_SUPPORTED)
     @Override
     public void findUsers()
     {
          if (availableUsers.isEmpty()) {
               availableUsers = (List<User>)entityManager.createQuery("from User u order by u.surname asc").getResultList();
          }
     }

simply does not cut it!

You get a very strange error from JSF...

Validation Error: Value is not valid

What this eventually came to (possibly) is that you need to override the default equals method!

Right or Wrong I used:

    @Override
    public boolean equals(Object o) {
         return this.getId() == ((User)o).getId();
    }

This now appaered to work until I persisted the containing entity and I got a detachedEntityException.. ARGH!

So had to add:

List<User> sponsorsToAdd = new ArrayList<User>();
          for (User eachSponsor : this.event.getSponsorDetails().getSponsors()) {
               sponsorsToAdd.add(entityManager.merge(eachSponsor)); // Re-Attach the Sponsor object.
          }

This seems a very big workaround to get this to work... is this kind of feature being addressed in JSF2?

As I have not actually persisted this yet due to other problems I still have not seen this work, but feel confident.