Persistent Message

The folks at 37 signals use a persistent message at the top of Backpack pages to alert users to new features (in the example below, the message is used to announce their affiliate program).

The message is persistent in that it continues to be displayed at the top of any Backpack page until the user clicks "Hide this notice." However, the wording of that link made me assume that there would be a way to show it again once it is "hidden." What actually happens is that the message is removed - I wasn't able to find a way to re-display it.