I haven’t really used the calendar part of the little clock I have in my gnome panel, since its integrated with Evolution, and I use Thunderbird for my mail and Google Calendar for my calendar.
The other day I decided to try out Evolution again—after all, you never know—and I subscribed to some of my calendars from Google Calendar, and they appeared automatically in the panel calendar.
Now I can have my calendars on my desktop 🙂
The calendars show up even without Evolution, because they are handled by the Evolution Database Server which can be used independently of Evolution.