This is pretty exciting for me. I just realized that I could sync my Ubuntu Gnome Desktop Calendar with my Google Calendar account. And also the great thing about it is that it is really easy to do.
First open your web google calendar account. On the left pane, under "My Calendar" and your email address, click 'Settings'. Then you will see the setting page. Click again your email address to get more detailed settings. On the bottom of this page you will see "Private Address". Copy the private ICAL url.
Once you have done that, open terminal and enter the following command:
$ /usr/lib/evolution-webcal/evolution-webcal YOUR_PRIVATE_ICAL_URL
Set the appropriate configuration if necessary, and you are done.
Now, to see the result, click on the Date Time info on the toolbar (above), and you should see the dates which you have activities (appointments) are marked bold. You should also see 'Appointments' list.
Enjoy managing your time and day with Google Calendar and Gnome Desktop.