This seems like a great way for newcomers to learn the basics of `git` though GitHub. A great move by GitHub to try to capture this market of users who may not yet be comfortable with subversion control.
Uhm, git was created by the people who were working on the kernel because they needed a better VCS.
I can't really knock it, but at the same time, this has been Microsoft's strategy for a long time, with students learning Office in school but no competitors, so they take it with them in their private and professional life.
It's a difficult one though, given that both github and office are pretty standardized / ubiquitous everywhere.