For any of you running the Thunderbird 2.x series, perhaps based on my tutorial on manually installing the latest Thunderbird, there has been a security patch released today. Below are instructions on upgrading manually, and a quick outline of some of the major security fixes.
Download Thunderbird (Save as...)
sudo tar -C /opt -zxvf ~/Desktop/thunderbird-*
One of the security patches looks specific to Windows, but the other could be Linux related. They are outlined below:
MFSA 2007-23 Remote code execution by launching Firefox from Internet Explorer
MFSA 2007-18 Crashes with evidence of memory corruption
Note: manually installing Thunderbird or any other application not from the official Ubuntu repository limits the level of support that can be received from the community. Please keep this in mind or know what you are doing.