> A regular "Who Is Hiring?" thread appears on the first weekday of each month (or Jan 2). Most job ads are welcome there. Only an account called whoishiring is allowed to submit the thread itself. This prevents a race to post it first.

> Another kind of job ad is reserved for YC-funded startups. These appear on the front page, but are not stories: they have no vote arrows, points, or comments. They begin part-way down and fall steadily. Only one is on the front page at a time.

I'm not sure either of those qualify as ads in the sense we're talking about Reddit ads -- the first one doesn't bring in any revenue to HN (or cost "advertisers" any money); the second one seems like it's a perk for "graduating" YC and it's unclear whether it's something HN makes revenue from, either.