Recent comment by PG on the outing of startups who anonymously post jobs: http://news.ycombinator.com/item?id=2022335. In my eyes such a thing falls in the "not-unethical-but-something-you-shouldn't-do" category. There's nothing strictly wrong with it since you are just using publicly available information, but it is a courtesy not to. Sure perhaps someone else will out a startup, but you don't have to be that guy.