Michael is correct. Thunderbird doesn't integrate with CouchDB (yet :) so the only way to get it to sync with the Ubuntu One cloud is through our mobile phone contacts sync service since Funambol (our technology partner) has developed an add-on for that application. They also have add-ons for MS Outlook and the Mac Address Book applications.
Currently their add-on does not support Thunderbird 3 (so jumpnett is correct) but they're working on supporting that version of the application.
Basically, you must tell Ubuntu One you have a mobile phone (you can fake it) and then install the mobile phone syncing plugin for Thunderbird and point it at Ubuntu One.
Michael is correct. Thunderbird doesn't integrate with CouchDB (yet :) so the only way to get it to sync with the Ubuntu One cloud is through our mobile phone contacts sync service since Funambol (our technology partner) has developed an add-on for that application. They also have add-ons for MS Outlook and the Mac Address Book applications.
Currently their add-on does not support Thunderbird 3 (so jumpnett is correct) but they're working on supporting that version of the application.
Thanks!
It is supported, but not quite as elegantly as Evolution syncing. Here's the step-by-step:
https://wiki.ubuntu.com/UbuntuOne/Tutorials/Contacts#Sync%20Thunderbird%20contacts
Basically, you must tell Ubuntu One you have a mobile phone (you can fake it) and then install the mobile phone syncing plugin for Thunderbird and point it at Ubuntu One.
As of 11.10 (a year and a half after you asked) the answer is a resounding "yes." At this stage integration works well.