Some years back when I was still actively working on POPFile and speaking at the Spam Conference at MIT I was invited to be on the technical advisory board of a company doing anti-spam work.
I flew up to the company's headquarters and met everyone and sat down for an interview with the head of engineering. At no time did he ask me a technical question. We discussed what was working and what wasn't working in the fight against spam. We talked about The Spammers' Compendium. But no one asked about my code.
I found out why towards the end of the interview when he said: "We've read your code".
Because I'd been doing all the development of POPFile in the open the company had evaluated my technical ability just by reading my code. And there's the great advantage of being open: others can evaluate you and choose you without you needing to apply for anything. And if you do apply then make sure people can find your contributions.
I've been lucky because "John Graham-Cumming" is close to a unique ID. There is one other who's a Detective Constable in Manchester (which is odd, because I seriously considered entering the police force after my doctorate). But, if you are "John Smith" then it's worth making sure that you have a clear online identity.
For years, I've cultivated my own identity through the web site jgc.org. I registered the domain back in 1997 to make sure I had my own place on the web, and to make sure that my email address would always be valid. And more recently I've built up places on Twitter and LinkedIn that potential employers (and others) can use to find out about me.
It's worth doing the same if you want to be Googleable. And my bet is that you will want to be, because if you don't then your online identity will consist of the things you haven't cultivated. Your identity will only look its best if you curate it.
And while places like Github and LinkedIn are important parts of your identity, there's nothing more important than a web site that you control. If you haven't registered your domain today, do it.