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.
For more information about Backtrack check out there website http://www.backtrack-linux.org or the wikipedia page http://en.wikipedia.org/wiki/BackTrack
Backtrack has been superseded by [Kali] Linux.
The image includes many of the security tools that the desktop version includes.
However the does not include tools like airocrack as this requires your wifi chip to be in monitor which most android devices do not allow, these tools can be installed view backtracks repositories if you do have drivers with monitor mode.
Unlike most other support distros our backtrack image only comes in one 'flavor' this is because a lighter version isnt possible without removing many of the tools that make backtrack what it is. (Backtrack without the security tools is just Ubuntu really)
The Backtrack image is created by using the prebuild ARM image found on the backtrack website http://www.backtrack-linux.org/downloads/ as a base image.
This image was larger than 4GB and so would not fit on a FAT32 formatted device (which most users sdcard are) so we made a new image of size 3.5GB and moved the content into this.
We then updated the packages within the image as the prebuild image was very old and alot of packages where very outdated.
A normal user (named backtrack) was also created as the prebuilt image just used the root user which is not a good idea.
Once this was finished added our startup script (init.sh) to the image which fixed alot of errors with the image (the prebuilt image was only designed for the Xoom).
Wiki: General FAQ
Wiki: Image Changelog
Wiki: Kali
Wiki: Supported Distros