GitHub continues to build out its unique social network with Contributions, a new addition to profile pages that displays the projects developers created and what they are contributing to, as well as a calendar that shows all of their updates.
Like a social graph, the repositories with the most starts and watchers makes it to the top of the list.
GitHub Introduces Contributions, A New Way To Display On Profile Pages What Developers Are Doing | TechCrunch
Given that your open source contributions have become a major part of your cv when you are a programmer this makes completely sense.
Github is making it easier and easier to show what you have created.