etckeeper is a collection of tools to let /etc be stored in a git, mercurial, darcs, or bzr repository. It hooks into apt (and other package managers) to automatically commit changes made to /etc during package upgrades. It tracks file metadata that revison control systems do not normally support, but that is important for /etc, such as the permissions of /etc/shadow. It's quite modular and configurable, while also being simple to use if you understand the basics of working with revision control.
the random number generator in Debian's openssl package is predictable
Massive scale installation and management tools for Debian GNU / Linux
warum "apt-get dist-upgrade" nicht immer besser ist als "apt-get upgrade"
kde debian package manager