What is truly fascinating is how this map/tool is how its being applied. ZDNet explores how the depicted population movements reflect support for former Alaskan Governor Sarah Palin and President Barack Obama. Meanwhile the conservative think tank American Enterprise Institute used the tool to compare the push-pull of Texas' conservative-minded development to California's liberal-minded development (Hat tip: Goethe Girl).
It is great to see that easily accessible geographic data is encouraging people to explore the geography and meaning of American migration. A Google search shows the map tool is very popular. If you can find another useful/neat/odd application of Forbes' map post the link in the comment section!