I noted the grant to Vizzuality (the folks behind CartoDB) from the Knight Foundation to build an open source tool for map-based storytelling back in January. This is not that. This is a tool from Northwestern University's Knight Lab. The lab is funded via that same foundation, hence the name.
This project, StoryMapJS, was in alpha in December. Now it's ready to test out in beta with enhancements that tap Mapbox basemaps and support for gigapixel images. It's still a work in progress: code contribution is not yet open.
StoryMapJS is a free tool to help you tell stories on the web that highlight the locations of a series of events. StoryMapJS is currently in a beta release. It is pretty stable in our development environment, and it has a friendly authoring tool.
New! Now you can use StoryMapJS to tell a story with photographs, works of art, historic maps, and other image files. Because it works best with very large images, we call these "gigapixel" StoryMaps. Learn more.
StoryMapJS is open source and offered under the MIT license. We still need to budget some time to adjust/document our process before we can really invite your code contributions, but if you're particularly interested, let us know.