Part of Mozilla’s mega-releases on September 7th, Mozilla Messaging has release the third update for Thunderbird 3.1 based on the Gecko 1.9.2 platform. For more information and to download please see the Thunderbird 3.1.3 Release Notes.
Further an update for Thunderbird 3.0 has also been released. For more information and to download please see the Thunderbird 3.0.7 Release Notes.
Next up in mid October will be Thunderbird 3.0.8 and 3.1.4.