Firefox updated to 3.0.1 and 2.0.0.16 to fix some minor updates and one major one – if you have Safari and Firefox installed. The “Carpet bomb” opened up the gateway in which a remote machine could take control of the computer. Safari released a fix back in June to plug this hole on their side.
Other fixes include CSS handling, GIF handling in Mac OSX, saving of SSL certificates and a “Offline” issue for PPP users on Linux. Firefox 2 also recieved a fix to stabilize the program if you run both Firefox 2 and Firefox 3.
As always, save all data before updating. Some Add-ons might need further updates. The only add-on I saw with an issue was a theme that I don’t run anyway.
For further information, check out the release notes.