There are three formal things that HN gives back to YC in exchange for funding it: (1) job ads, which appear on the front page and later on https://news.ycombinator.com/jobs; (2) Launch HNs for YC startups, which appear on the front page and later on https://news.ycombinator.com/launches; (3) YC alumni usernames display in orange to other YC alumni (though not to themselves, which has led to a stream of emails over the years).
https://hn.algolia.com/?dateRange=all&page=0&prefix=false&qu...
We explicitly don't do anything beyond that to favor YC or YC companies on HN, though we don't draw lines to exclude anything either, because YC-related people and content are an inseparable part of the community here.
I really need to add this to the FAQ though.
Hell they could just tag articles related to YC companies with a special color and pin them for a bit. I'd be fine with that.