That's kind of like the "hidden project" criteria, except public. Back when I wrote this article, I was only just starting to get to grips with the open source community (after using its products for a long time).

I think phrased as "has released things publicly", it's a bit too restrictive, because some people will be excellent programmers but just not have gotten into the whole open source community thing.

That said, from the point of view of helping narrow it down for someone who doesn't know programming much, then yes - if a programmer has released public libraries/applications that are in use, that's a great form of "extra-curricular" not-so-hidden project, so it could well be used as an additional indicator.