I also discovered today that Backtrack is no longer supported. I tried to update my Backtrack 4 but it would not connect to repository. I tried to download Backtrack 5 from the website, but nothing happened when I clicked the download button. It was very confusing, as there is no indication the Backtrack website announcing that it is no longer available and that it has been replaced. I only found out by chance searching for a Backtrack torrent, someone commented it was replaced by Kali.
Right away I downloaded latest SARDU to see if it had been updated for Kali, but it has not

*MD*