Google visualization API

Released, blogged here: http://google-code-updates.blogspot.com/2008/11/introducing-powerful-visualizations-for.html

Nice example here: http://jpbi.blogspot.com/2008/03/motion-chart-provided-by-google.html#

Home here: http://code.google.com/apis/visualization/

Also on a related note: http://www.gapminder.org/ (check the links section too)