I have the CDN correctly configured to Amazon S3 and I'm using a woothemes.com theme.
Within the theme, some images are stored within custom fields per page and then delivered as text block and images. There are six examples on the home page at http://www.massivemouse.com.
Without the CDN in W3TC enabled, these images appear. With the CDN enabled, they disappear. I realize that this is probably a file location/specified address issue, but I haven't been able to figure out exactly what the problem is.