Mozilla has released a new version, 13.0.1, of its Firefox Web browser, for all platforms: Mac OS X, Windows, and Linux. This appears to be primarily a bug fixing release, addressing problems with Windows Messenger and Hotmail, Flash player, and rendering of Hebrew text. More details are available in the Release Notes. There do not appear to be any new security fixes.
If you have enabled automatic checking for updates, Firefox should inform you of the new version. Otherwise, you can obtain the new version via the built-in update mechanism (Help / About Firefox / Check for Updates), or you can download a complete installation package, in a variety of (human) languages.