It Works with Thunderbird 3 RC1 Rated 5 out of 5 stars
Version 0.9.10 installs in tb3.0 RC1 and works just fine in Linux. I don't know why but a few address I know I upload before trying TB RC1 are no-longer in my address book. But just to be sure I cleared my address book and restarted Thunderbird and Addressbook Synchronizer download everything just fine minus those address.
The final word is its working for Thunderbird 3 RC1 in linux. So try it out!
Download it at http://www.ggbs.de/extensions
Thanks for this great extension I have loved using it.