Adam,
I tried that and it works when I add the new room through the chat admin area. I just assumed it would read the rooms that already existed. Is there a way to keep and chat link in the forums AND have a separate tab for chat.aspx...and both of them send people to the same rooms? I tried setting up the new room, then assigning the Forum:18 (or whatever number), but then it dissapeared from the chat.aspx area.
EDIT: Actually, I don't even have to create a new room. As soon as I remove the integration text (ex: Forum:18), that room shows up.
Also, on this forum area, the page refreshes and erases what you're typing if you don't enter it quick enough!