This morning at YAPC I attended an Intro to Git session presented by Randal Schwartz. It was an awesome session! I learned a lot about git and how it works (and how you shouldn't try to make it work). I was typing up notes to post for y'all, and then he mentioned at the end that he has both the slides and a video of the presentation (a version he gave in January) available online.
So, if you have a spare two hours and would like to learn about git, here you go:
Introduction to Git - videoIntroduction to Git - slidesThere's also a book that many people have highly recommended, called
Pro Git by Scott Chacon. It's available free of charge in many formats, licensed as CC-BY-SA-NC.
I definitely felt much more comfortable with the idea of what git is, how it works, and why it does what it does when I finished the session, so if you're feeling anxious about the migration to github (which is a service layered on top of git, the underlying software), definitely check it out.