Type in a message and it'll become a pop-up for all users in your roster.
Moderators only feature. It would get rather annoying for other users if people decided to have their chat on everyone elses screen.
Don't really get this feature. I don't think it's needed though, as we've got conferencing. Possibly another redundant feature?
Yup. It creates another temporary chat room, which only the admin have that power anyway.