The company I work for is using gmail for email now and so we are also using google talk/chat/IM. One of the things that went missing with that migration was the ability for a comfortable easy access chat room, that we had when we were running our own openfire server.
Google has some notes on doing multiuser chat when using the talk gadget etc, which is described in About group chat. The thing about this is that you have to create it new every time, rather than having a persistent place to go.
The other day I was lamenting the lack of a chat room and decided another search was in order. Much to my delight I stumbled across a thread on ubunutforums that told me what to do.
In a nutshell you need to generate a unique UUID
Then, in the Empathy contact window click "Room -> Join" and in the following window enter:
Account: <pick one of your google accounts>
Note the private-chat- at the beginning of the room name. It seem to be needed. Then, voilà, you have a chatroom that you can rejoin. Make sure you mark it as a Favorite in the Room menu.
The one thing that is ugly about that is the fact that it uses that aweful name above as the name that is display. There seems to be no facility to assign an alias or change the name in Empathy, but a little file editing can overcome that.
Simply open up the file $HOME/.config/Empathy/chatrooms.xml and change the XML for the <name> to something more palatable.
One thing that irks me is that when you rejoin the room it always starts with empty slate, while pidgin users have the option to pull that history in.