Distributed SCM - Mercurial

Introduction: from http://hginit.com/:

Hg Init: a Mercurial tutorial
Mercurial is a modern, open source, distributed version control system, and a compelling upgrade from older systems like Subversion. In this user-friendly, six-part tutorial, Joel Spolsky teaches you the key concepts.

Joel太能吹了。推测他之所以写这么一堆介绍材料，是因为自己的公司在Mercurial的基础上开发了一个SCM系统。

Wikipedia（http://en.wikipedia.org/wiki/Comparison_of_revision_control_software）例举了很多SCM系统以及它们的比较，值得一读。