Comment 5 for bug 569191

I found a fix for this not sure how much is necessary but his is what I did to get it working.

Open gconf-editor
 go to /apps/avant-window-navigator/awn-applet-calendar/

set url to your private address under your calendar details in google calendar
add your username
leave your password field blank

restart awn
you should get a pop up asking for your password enter it and save the password

that got it running for me.