Interesting Things
Engine Yard has made some changes to their ssh-key setup:
...any non-approved keys will be removed from the root user's authorized_keys file. It should be noted that customers should not log in directly as root but rather should log in as their user and use sudo for any commands that need super user privilege. If you are currently using the root user to log in and have your key in roots authorized_keys file it will be removed when this change is made.
If you are having any ssh problems, contact them.