Mozilla just released Firefox v1.0.2 and Thunderbird v1.0.2. Whats New?
Firefox: Security Updates Thunderbird: Security Updates
These minor updates will not change much and most people will not even notice any differences. They have also fixed few bugs and prevented some types of crashes. But anyways download and install the program to be safe. (Note: 1st uninstall any versions of Firefox or Thunderbird, then install the two programs. If you uninstall and re-install either of the programs nothing will be lost will be exactly the same after finishing installation. This means all emails, bookmarks, settings, accounts, and so on.)
Link: Mozilla | Firefox | Thunderbird | Extensions