I'm getting into a bit of both client and server side development, and in looking around, I see a lot of developers pointing to Github profiles. I've also seen many job listings ask for the same.
I'm curious, how important is it to build a repository for either serious consideration as a job seeker and/or reputation as a hacker?
What do you hack? No one would argue that someone who is a core developer for, say, Emacs isn't a hacker merely because Emacs uses bzr for source control.
Github is a means to an end: simple sharing and collaboration of code. If your hacking doesn't require that, don't get a github account. But if you can't point to what you've done -- this is not necessarily "show me the code"; if you build a website that does something cool, or hack some hardware, that'll count -- you're probably not a hacker.
Worry about your projects, not github.