We use Thunderbird to access Gmail through IMAP.
The application just alerted us that an update was available.
It turned out that it the stable edition of Thunderbird 3.0 has been released.
Mozilla Messaging website has no updates related to the release of Thunderbird 3.
Mozilla Thunderbird 3.0 Release Notes Page (Not working currently. We were directed to this page from the updater).
We expect to see an official release statement in the coming hours.