http://www.mozilla.com/en-US/thunderbird/2.0.0.19/releasenotes/
I got notice of the update.
Still using Firefox 2.0.0.20 and looking for info as to when Firefox 3.1 will be released (supposed to be after the 2nd beta but now Mozilla said there will be a 3rd beta so I guess it will be spring before it's ready for full release).