Right now, we integrate both with GitHub as a "Repository provider" and Heroku as a PaaS.
If you connect your Github account we'll import your GitHub repositories.
And we do have a primitive and slightly awkward way of pushing back to your github repository. That will be improved in the coming days. To make it more obvious and easier.
Thanks for pointing that out. We want to integrate as well as possible with current existing services.
There is no need to reinvent the wheel regarding code hosting and we want to focus on what makes us different.