For anyone trying to connnect to any of the Jabber rooms on Transneptune, there appear to be some issues concerning GTalk at the moment. The short of it is that GTalk will currently not show messages from an entity unless you are subscribed to that entity, which is fine for individuals, but when trying to use a chatroom, breaks. So GTalk users can connect to the room, and send messages to it, but cannot receive messages back.
Until this is resolved (which may require action on Google’s part; I’m still investigating), just connect with your Transneptune account if you want to use the chats.