[electroagenda]

I think that question is more complicated to reply than it looks like.

From the point of view of HN, it should be better to open in new window. That avoids users going out of your page.

However, as a blogger I have discovered the technical audience annoys enormously when links open in a new window. People get angry because you always have the shortcut to choose the new window if you indeed desire that.

So, to me, HN has decided to please its audience at the cost of loosing pageviews.