Lightning: Mozilla Thunderbird Calendar Add-in

This has probably been around for a while. However, I only learned about the Mozilla Lightning add-on calendar project for the Mozilla Thunderbird email client (another on my must have list) a couple of days ago. It is listed along with the better known (to me anyway) Mozilla Sunbird standalone calendar client as a calendar project. I hope this add-on doesn't fade away along with Thunderbird after it is split off from the main Mozilla group.