Rated 5 out of 5 stars

The new pre-release is available for Thunderbird 5.0 :
http://extensions.sanjer.nl/index-site.php?page=tb_cs_prerelease

Thanks to Jeroen Peters !!!

French : http://infos-pro.bossy.fr/1/post/2011/07/contacts-sidebar-et-thunderbird-50.html

This user has other reviews of this add-on.