The Party Scroller makes use of several servers and several scripts to get a message from your phone to the sign. Basically, heres the gist of it: The user sends a text message from their phone to my Google Voice number, which will then send an email out to a special email address which pipes the email into a PHP script. The PHP script will extract the necessary data from the email, and put it into a database. Meanwhile, another computer is continually checking the database for a new message every 20 seconds. When it sees a new one, it will grab it from the database and display it on the board.
[Source] plasma2002 via Hack-A-Day