This one's got me stumped. I'm setting up a dev version version of my app and for some reason the iframe is not receiving the HTTP referrer header.
The app I'm working on relies on that header being sent. Can you think of any reason why the iframe wouldn't be receiving it?
The app (no referer): http://apps.facebook.com/colinlocaltms
A link to Canvas URL (has StackOverflow as the referer - expected since you're clicking the link): http://secret-lake-4762.herokuapp.com/