To those in software development, version control can be both a godsend and a devilish frustration. Git solves many of the challenging problems users of systems like SVN and CVS encounter, but it can take a little learning to start using appropriately.
I've started using Git for my Archdiocesan web development (see issues for setting up Git on a CentOS server, and setting up a local development environment for Git/database/file synchronization), and it rocks. So much more so than SVN.
During the month of October, Nettuts+ (an online training site) is offering it's $10 'Getting Good with Git' eBook for free, and I have to say it's a great Git primer, with a ton of great information, both for those who have never used Git, and those vaguely familiar with Git.
For Drupal developers especially, this eBook is a great find, as Drupal will soon be switching all its code repositories from CVS to Git.