Can anyone shed some light on the Hacker News story ranking algorithm?

After 1 hour, this submission was in third place on the front page, then I checked again about 15 minutes later and it had dropped to 93rd place, on page 4! There are many other stories that are both older and have fewer points that are higher up the rankings. Judging by the number of comments, this link is obviously a story of interest to HN.

Just curious what's going on..