Using Shotwell, I discovered that to publish to Flickr I need to set up an online account. But the online-accounts system settings only has support for Google, Facebook, Windows Live, Microsoft Exchange and Enterprise Login (Kerberos).

How do I add account types?

These appear to be properly installed (dpkg-reconfigure returns silently):

• gnome-control-center-signon is already the newest version.
• account-plugin-yahoo is already the newest version.
• account-plugin-flickr is already the newest version.

Here's the config file (I think):

> cat /usr/share/applications/gnome-online-accounts-panel.desktop
[Desktop Entry]
Name=Online Accounts
Comment=Manage online accounts
Exec=gnome-control-center online-accounts
Icon=goa-panel
Terminal=false
Type=Application
StartupNotify=true
Categories=GNOME;GTK;Settings;DesktopSettings;X-GNOME-Settings-Panel;X-GNOME-PersonalSettings;
OnlyShowIn=GNOME;XFCE
X-GNOME-Bugzilla-Bugzilla=GNOME
X-GNOME-Bugzilla-Product=gnome-control-center
X-GNOME-Bugzilla-Component=Online Accounts
X-GNOME-Bugzilla-Version=3.4.2
X-GNOME-Settings-Panel=online-accounts
# Translators: those are keywords for the online-accounts control-center panel
Keywords=Google;Facebook;Flickr;Twitter;Yahoo;Web;Online;Chat;Calendar;Mail;Contact;
X-Ubuntu-Gettext-Domain=gnome-control-center-2.0

History: Started out with Ubuntu (64-bit), then in 12.04 installed xubuntu-desktop and have been using that. Upgraded to 12.10.