Is it worth posting something like this to Hacker News? HN readers who subscribe to The New Yorker probably caught the article anyway; for others, obtaining access is costly. But the article, if it were freely available, would clearly be of interest to the HN community. And HN readers who do have access to the article might enjoy using HN as a forum to discuss it.
Another possibility is to wait to post the article until it's made freely available; Malcolm Gladwell apparently posts everything he writes for The New Yorker to http://malcolmgladwell.com/ six months after first publication.