Mozilla has released an update for Firefox, version 3.5.4, that includes some important security updates. Other than security and stability issues fixes there are not much notable changes in this version. You can read through the full change log here.

Mozilla will push these updates sometime tomorrow and your Firefox will notify you about the update. If you don’t want to wait till Mozilla pushes  the updates, you can start the update process by following the menu options "Help -> Check for Updates".