Is the subscribe link at the bottom of that page specifically for this type of stuff? There is nothing visually connecting that to the article and it only uses the vague phrase "updates from Y Combinator". I am one of those HN users who comes here for the tech topics much more than the startup topics. I therefore don't have much interest in Y Combinator outside of being thankful that they host this site. I don't really want every blog entry they post to be emailed to me but I will happily sign up if it is more this type of content.
It's all the blog entries, but usually formatted fairly well. There aren't too many blog entries (five or so), and typically ones that make HN are highlighted more.