Overall, my post spent about 8hrs on the front page of Hacker News, reaching as high as position #5 (HN has a time-based curve - your post will only stick if it's young with a fair few points, or old with masses of them.) It eventually garnered 93 points and 38 comments. People clicked the Twitter button 101 times (which amazes me, since I didn't even bother doing that and I wrote the damn post) and Facebook 'like'd it 43 times. Clearly a bunch of people manually tweeted about it too, since there were lots of differently formatted tweets about it when I searched.
My webhost's statistics say it was viewed 23841 times and Google Analytics - which I only thought to install about an hour after posting it - tracked just under 17000 unique visitors (obviously missing the first few hours.) In an attempt to work out whether this was representative, I found a few other people discussing the effect on their posts; David Zhang of simply.io, the guys at elastic.io, and a few others. Nowhere near enough data for a representative sample, so label this inconclusive.
Of these visitors, the bounce rate (the percentage of visitors who leave without navigating to another page of the website) was 90%, and a different 90% stayed for less than ten seconds. Ouch. On the other hand, I guess that suggests that those who did actually read the article "converted" by looking over at least something else. In terms of page depth, 5.63% hit two pages, 1.57% hit three, and exponentially lower thereon. It was a long-ish post that probably took two to three minutes to read fully; roughly 1500 visitors stayed at least that long reading it and/or other pages.
The final four were preliminary job offers - I don't mean "this job pays $X and if you say yes you'll start on monday", but more like "you sound like you might be interested in and the perfect candidate for this job, let's have a chat about it". This is the valuable bit. Compared to sending your résumé into the lion's den of HR and hoping your choice of perfumed paper makes the grade, having potential employers come to you instead is a far more pleasant way to operate. I even got a free lunch out of it yesterday - they do exist!
To summarise the Hacker News effect; it's definitely valuable. HN gets ~150k unique visitors in a day. The vast majority only view the front page. Given my post was there for about 8 hours, let's assume 50k of those uniques saw it, which means nearly 50% clicked through. Of those, 90% abandoned it immediately. Of the remainder, only about 10% abandoned before finishing the article, i.e. around 9% of the total HN traffic read the whole thing. This is in agreement with a BoingBoing article that discusses the readership habits of various traffic sources (the original source is here, but the graphs are broken), concluding that HN readers stick around longer than those from any other referrer. Of the attentive HN traffic, around 50% read something else on my site, around 10% tweeted, liked, commented, or somehow promoted it on, and about 2% got in touch with me directly.
If you've read this far, you probably shouldn't follow me on Twitter because I've got very little idea why it's important.