To be honest, I posted this: http://news.ycombinator.com/item?id=2364399
It never made it to the Front page, but has been close to the top of the second front page, and even after falling off the "New" page it still garnered the occasional vote. That suggested that people either were clicking through, or had marked it as "Read Later" and then did so.
I wondered how many people saw it at all, and hence the question.