Check your IMAP path.... Preferences --> Accounts --> Account Name --> Advanced --> IMAP PATH PREFIX.
Check to see if Thunderbird has a setting for it, and using that instead of the default of "". If you find it in thunderbird, try changing it to that... Otherwise, Try removing that, and saving the changes...
Mail will probably re-sync, but you should then see your mail, and subscribed folders.
It may also be that MAIL.app doesn't fully support IMAP subscriptions...
See http://discussions.apple.com/message.jspa?messageID=7122662
After reading the discussion thread further, and exploring a little here myself... I believe that the Subscription List is only really enabled for Exchange Servers.
My Gmail accounts show blank subscription lists... But my exchange (work) account shows the public folders from the Exchange Server.... So that leads me to believe that this feature is really intended for exchange support...
I had 'INBOX' as the prefix. Tried after deleting it, but still the subscription list is empty. – Shoan – 2009-11-19T08:26:14.153