i dont see huge value added by looking at someone's github, maybe they dont use it, maybe they published someone else's code, maybe it was done in a group project and they didn't really do anything, maybe its private, etc etc. i'd rather see a portfolio of things (end products) they have done, see what they are excited about, and ask them about it.

like 'oh, you learned ROR on your own while doing your undergrad and made site x?' and go from there.