BackTrack is a Linux-based penetration testing arsenal that aids security professionals in the ability to perform assessments in a purely native environment dedicated to hacking. This release comes with faster Desktop responsiveness, better hardware support, broadersupport, streamlined work environment. It also has the new kernel. The new BackTrack 4 R2 (bt4-r2.iso/bt4.R2-vm.tar.bz2) has been in production for almost 3 months, has been updated yet again!
Source: https://thehackernews.com/2010/11/backtrack-4-r2-new-release-download-now.html