Wordpress on Heroku
young-journey-5257.herokuapp.com
young-journey-5257.herokuapp.com
You may run into problems with any other plugins which use MySQL specific SQL syntax though.
Or, even better, use a Linode image with WP already installed, boot it and you're in business.
http://core.svn.wordpress.org/tags/3.2.1
and then deploy to Heroku directly using git.
edit: actually, I think the upload to S3 button is different from upload media button. That's why I didn't see it.