MaZderMind/Thunderbird-CardDav — Issue #1: Take a look at SoGo Connecter
Author: carlos22
Created: 2012-01-03 23:16:51+00:00
State: open

This is a CardDAV sny for TB, but only 3.1.
Link: http://www.sogo.nu/downloads/frontends.html

Maybe you can modify it and get it working with later versions of Thunderbird?!