If you were interviewing at my company, we'd ask you if you had a github account (or some other public code repository) quite early in the hiring process.
Depending on your responsibilities we'd then look for specific traits (actually more the absence of undesirable traits) so that we'd get a feeling of
- your actual capabilities versus your claimed experiences
- how much training would be necessary to integrate you into a project team
So, along with my predecessors, I strongly recommend including it.
Edit 04/2016: re Undesirable traits
Happy coincidence ... just a few days ago I came upon this piece, which nicely sums this up for the "programmer" side of employees.
On the "personality" level ... difficult to say without getting into a lengthy monologue. Recently one of my clients complimented me on how I always manage to project calmness and listen to them, think about problems before presenting a solution, while other consultants "just want to do their thing" and charge heavily. To which I replied "I left my ego tied up in the trunk outside in the parking lot". They have also heard "I don't know, I have to look it up", "Interesting problem, let me experiment a bit, no charge", "I could do that but if you just buy X, you'll be better off" from me.
TL;DR: rock stars, code ninjas, pure tech wizards: no. Generally Competent Human: yes.