Blog Post: http://www.tonyamoyal.com/2010/04/27/getting-fancyupload-to-work-with-rails/

Steps to make the example work:

- Make sure you have the HAML gem installed

- Make sure a public readable crossdomain.xml exists in your /public directory:

<?xml version="1.0"?>
<!DOCTYPE cross-domain-policy SYSTEM
"http://www.macromedia.com/xml/dtds/cross-domain-policy.dtd">
<cross-domain-policy>
  <allow-access-from domain="*" secure="false" />
</cross-domain-policy>

- Also make sure a folder named ‘data’ exists in your Rails root. Files are uploaded there by default but this can be changed.