git is the SCM developped for the Linux kernel after the famous affair with proprietary Bitkeeper system. There are good tutorials for git (for example, the official one) and a fun video talk with the “Linus touch”. I’m “yet another victim” of the buzz^Wpopularity of git (particularly in the Debian community):
git://git.debian.org/git/collab-maint/pppoeconf.git