So what should happen do you think?  Ignore them?  Put them in a *special* group?

I suggest not showing them at all, I don't have them in my roster so they should
never be visible to me.

Mmm, I am thinking about special cases, like multiple resources showing in the
roster when they are not actually on your roster might be a problem there (since
you don't usually have yourself on your own roster).

There may be other instances too I haven't thought of.

I am not sure it is a good or bad idea to be honest.

It's just a bug, it's not a design issue... 

This is what happens, say that someone called Foo for some reason sends me
presence, maybe I'm in his list, or the rosters are out of sync or something. 

When I start gossip, I don't have Foo in my list, since when the roster is
received from the server, he's not in it. Then Foo for some reason sends a
presence message, the contact list happily puts it in there. So I won't have
that person in my list until the first time he has sent a presence message. Even
if he is onlike for three days before, I won't see him until he's changed his
presence.

When trying to remove the contact, (right click, remove), sure he goes away. But
only until the next time he changes presence, pop, he's back. Clearly a bug :)

I don't know why you'd want yourself in the list, I certainly don't want that
when I'm online with several resources. But that could be special-cased if there
are any reasons why that would be a good idea.

OK you got my vote, :)
I will see what I can do. 

Yes, this is most likely a simple bug to fix and explains why I thought I
couldn't "remove a contact" the other day :)

I have committed something that works OK.  

It will not show people NOT in your roster and it will not show other connected
resources using the same account.

Should we be showing other resources on the roster?

Closing this bug, since it has been fixed, no resources, group chat rooms or
unknown contacts have turned up on my roster.