"Git is software that is responsible for keeping track of changes to a set of files that are commonly called repository."
Something as simple to understand, and people are still afraid. I've got some articles quite interesting, and although we have alternatives like SVN, every day is getting more followers.
I leave several links to not miss anything of this version control system.
¿What's Git?: fuenteabierta
Mini-tutorial about Git: ubuntu-españa.org
Git Server with Gitolite: paraisolinux.com
Learn Git on 15 minutes (english): try.github.com