You should check out etckeeper, a package that does exactly that. Additionally it will hook into apt-get and similar system tools and automate Some of the revisioning
https://help.ubuntu.com/10.04/serverguide/C/etckeeper.html
Example of using etckeeper with Git on Ubuntu 10.04 LTS:
http://evilrouters.net/2011/02/18/using-etckeeper-with-git-o...