Important: At least in the Thunderbird 11 Daily builds, you will need to manually update Lightning by going the the Calendar Versions page then down and install the correct version.

As mentioned earlier this week Mozilla Lightning, the Thunderbird Calendar add-on had been updated for Thunderbird 8. The Calendar Versions page on MDN now shows new versions (with an entirely new numbering scheme) of Lightning for the upcoming (channel merges are still in progress) Thunderbird 9 Beta, Thunderbird 10 Earlybird and Thunderbird 11 Daily builds. As odd as the old numbering scheme was, it did sort of make sense (compared to the new numbering scheme that is).

Also, there is a new version of Provider for Google Calendar. Version 0.9 was released on November 7th as well and shows it is only compatible up to Thunderbird 8. However, it can be successfully updated manually for the later developmental versions of Thunderbird. To update manually, you will need to download the add-on from the AMO page. Once downloaded, locate the add-on in Windows Explorer and drag into your Thunderbird add-ons manager. If this method does not work, click the Gear menu in the Thunderbird add-ons manager and select Install Add-on From File…