Publishing a message with an expiration date

Hi all,
I have built some sites for smaller business companies, they prefer static pages rather than posts. Sometimes they will put just in their main page a short message like “Next Saturday we are closed”, it should be just in the top of the mainpage, no widgets, at the very most styled with another background color. However it could be practical that they don’t need to worry about removing the message after that particular Saturday. I am thinking about writing a little plugin with a shortcode something like [shortmessage start="30/04/2013" finish="03/05/2013"]Next Wednesday we are closed[/shortmessage] and my customers will be able to work with it but I would like to know if there are more practical methods or plugins that already exist. Thanks for any help