Their vision: "GWHAT's goal is to improve the world's understanding of how we arrived where we are by providing an animated, map-based, storytelling environment. The web is full of wonderful map content provided by amazing map producers. GWHAT aims to make this content easier to find, easier to contrast and compare, and easier to customize. Historic information should not be captive to data formats, copyrights, or subscription barriers."
They don't seem to offer much map storytelling content yet.