As of the fedora-release today, I see that two of my F9 systems worked
fine and transitioned properly from the old keys to the newkey. On
the first one I used GNOME and PK. On the second one I used the yum
method, excluding 'yum' and 'yum-utils' as noted in the Known Issues
section of the wiki.
If have one comment however. On both cases, the full fingerprint of
the key wasn't displayed for checking by the user. The PK dialog that
prompts the user to import the new key doesn't show the full
fingerprint, and neither does yum iteself--I think this is an
unfortunate omission for both PK and yum. The keyid alone isn't
enough to verify the key with.