It looks like Bitnami expects the Rails app to be in url/appname. So, I just removed the /ndeavor from the thin.yml and from nginx.conf.
This is what my thin.yml looks like now: https://dl.dropbox.com/u/35302780/thin.yml
And this is my nginx.conf: https://dl.dropbox.com/u/35302780/nginx.conf
I'm using Bitnami Rails stack that runs Ubuntu.
I now start the Thin with this: thin -C thin.yml start
And I start Nginx with this: bitnami@linux:/opt/bitnami$ sudo ./ctlscript.sh start nginx
And they both start OK.
But, when I go to my website url, I get this message "The service is not available. Please try again later."
I don't know where that message is coming from.