Hacker News Reader

My bet is on AWS, but I'm also rather curious about this.

You're rather mistaken my friend. Hacker News existed a long time before AWS. It has 2 servers - 1 production, 1 standby, running FreeBSD.

FreeBSD is the OS of choice for them.

Perhaps I misunderstand your remark, but AWS (2006) predates Hacker News (2007). According to Wikipedia, that is.

EC2 was only in limited beta back in 2006. It wasn't in full production until 2008.