Kali Linux 1.0 was announced today during Blackhat Europe. Kali Linux is a derivative of the Debian-based Backtrack Linux.
Kali was developed in private until now by the developers behind BackTrack. Kali is already being advertised as "the most advanced and versatile penetration testing distribution ever created."
New with Kali is streaming security and package updates from Debian, Debian compliant packaging for Kali tools, a streamlined development process, improved ARM support, and seamless upgrades between major releases.
This new security-focused Linux distribution can be downloaded at Kali.org