Tails, The Amnesic Incognito Live System, version 0.12.1, is out now. This is a brown paper bag release aimed at fixing two major problems introduced in Tails 0.12. While upgrading is recommended, it's not strictly necessary for users that haven't experienced any issues with Tails 0.12.
 
About Tails
The Amnesic Incognito Live System (Tails) is a Debian-based live CD/USB with the goal of providing complete Internet anonymity for the user. The product ships with several Internet applications, including web browser, IRC client, mail client and instant messenger, all pre-configured with security in mind and with all traffic anonymised. To achieve this, Incognito uses the Tor network to make Internet traffic very hard to trace.