Personally, I think "Installing and Running a GNU/Linux Environment on Any Android Device" is a bit misleading. The GNU/Linux environment is just an application

Personally, I think "Installing and Running a GNU/Linux Environment on Any Android Device" is a bit misleading. The GNU/Linux environment is just an application running alongside Android. There are a number of similar apps available for Android, most of them rely on chroot to accomplish what they do. I wrote SSHelper, which does something similar (without using chroot) -- it provides Busybox and a command-line environment, but it's just an application, it doesn't replace Android. Using chroot creates a more complete environment, but all these solutions rely on Android being present in the background.