[Update 10/5/2011] BT4r2 is now superceded by the new and improved BackTrack 5!
BackTrack 4 r2 (codename “Nemesis”) has been released and brings a number of updates aimed at improving “desktop responsiveness, better hardware support, broader wireless card support, streamlined work environment”.
Updates include an updated kernel (22.214.171.124) with improved wireless support, USB 3.0, faster responsiveness, pruned and new packages, and a new BackTrack wiki for more documentation and support.
Users with existing BT4 installs/VMs can simply perform an update using:
apt-get update && apt-get dist-upgrade
BackTrack 4 r2 is available as a 2GB ISO, or 2.4GB VMWare image, on the
downloads page (the BT4 download links appear to have been removed in favour of BT5).