GIS Day is November 14th, 2007. According to http://www.gisday.com, "on any given day, more than two million people around the world use GIS to improve the way their organizations see [users]. GIS Day provides an international forum for users of geographic information systems (GIS) technology to demonstrate real-world applications that are making a difference in our society."

See http://www.gisday.com for the latest GIS Day news or to register your own GIS Day event (http://www.gisday.com/events/register.html).