First a forewarning:
I’ve uploaded a first cut of a multi-item addon that contains my modified Weave addon for Thunderbird, and Weaver, an extension to Weave that adds address book syncing (local and collected books). You should only download Weaver if you’re comfortable using experimental development builds of early release addons that may cause your computers to burst into flames. I’m putting this out there to get a little feedback and make it easy for a few others to try out. When I’m more ready to consider a release, it will end up on AMO.
Actually, it works quite well I think.