Yes, they do. However, adding the second is not the default, so announcement that it's not going to be added is not as interesting. Also, I doubt "time libraries" "people" get their news from HN, on a day it could happen.
On the other hand, the HN public is one that should be acutely aware of leap second issues, because it's urgently necessary that all programmers should have some basic knowledge of this issue. So it's a good idea to draw attention to this a few times per year.
