In their user control panel, they had a place to enter a message and send it. It showed up exactly like yours does in the header.
It lasted 10 minutes, but would only show up one time for any user. After that the message would be gone. If another user came along and sent one, I don't know if that knocked out the one before or if they were stored in a table and displayed in order.
I don't care too much about whether they remain on the board longer than 30 seconds. I just would like to make the functionality available to the posters. It would be nice to be able to turn it off completely in the admin panel though in case it gets to be too much.