how to create a room in gtalk with Empathy (also works with Pidgin):

"1) Connect to your google talk account with Empathy
2) In Contact List click on Room then Join
3) Make sure you have you google account selected
4) The room name must be "private-chat-<uuid>" (check below how to get uuid)
5) The server should be "groupchat.google.com
6) Click join!

In your terminal run "uuidgen" you will get a number similar to this "c9e943d0-ec5a-47d9-9151-c5c35d971e34".

So your room name will be

private-chat-c9e943d0-ec5a-47d9-9151-c5c35d971e34

Thats it."