Rated 4 out of 5 stars

Quite good extension but is there a way to synchronize the lists as well ? I made several tests (thunderbird-zimbra) but never succeed in doing this...all my contacts are syncing but not my lists created either in thunderbird or zimbra.
It's the only (but important) annoying point but may be there's a way to solve it ?
Many thanks

This review is for a previous version of the add-on (0.8.13.3). 

TheMerse, version 0.8.15 onwards syncs Google groups with Thunderbird addressbooks. The feature is described here:
http://www.zindus.com/blog/2009/11/09/sync-google-groups-with-thunderbird-addressbooks/

For an explanation of why Google groups are synced addressbooks rather than mailing lists, see: http://zindus.com/i/mailing-lists
(relevant to Zimbra too)