There are many scientific groups where even today, no form of version control is used, even for internal work, so Github is way ahead of what is current practice in many places. There is a lot of good scientific code in various repositories and I don't see why anything special is required. As computation becomes even more important across many scientific areas, there is a lot of need for discipline. If scientists learn how to use version control and repositories just by default, that will go a long way towards reproducibility.
The Galaxy project does a great job of trying to foster such an environment:
> There are many scientific groups where even today, no form of version control is used, even for internal work ...
Where I work (government research lab) people think of Subversion as a sporadic backup target, typically doing a commit every month or so, despite making frequent changes to operational code.
Paradoxically, one scientist I spoke to was scared about overwriting code if he did an incorrect commit, but he's perfectly happy to have mycode.py, mycode2.py, mycode_this_one_works.py, mycode_this_one_works3.py, ...
The Galaxy project does a great job of trying to foster such an environment:
http://genomebiology.com/2010/11/8/R86
http://galaxy.psu.edu/
https://bitbucket.org/galaxy
http://wiki.g2.bx.psu.edu/Tool%20Shed