Rated 5 out of 5 stars

Addition to my former text:
I found a way to install Google Calender 1.0.1 (after it was deinstalled):
- download the xpi file from this website
- rename it (simpe name: e.g. Google_calender)
- open addons menu in Thunderbird
- drag and drop the xpi file in addons menu
- restart Thunderbird
- add new calender...

Michael

This review is for a previous version of the add-on (1.0.1).  This user has a previous review of this add-on.