Ask HN: What determines Hacker News frontpage status?

First I want to say I thoroughly enjoy being part of this community. I joined in June 2007 and Hacker News has been a destination I visit multiple times a day since.

Though I am curious how HN frontpage news is determined? Is it algorithmic or it's controlled by editors at YCombinator?

I am asking because out of nowhere a fellow HN reader graciously, posted a link to our start-up CodePupil.com. We were FORTUNATE to have this post appear on the front-page for 20 minutes. .

First we want to say we are flattered that another HN reader thought enough of our work to create a post about it. Thank you very much!

We were even more thrilled when it had the fortunate to land on the front page http://bit.ly/yOvn9t for 20 minutes.

Of course we wished the post could have been up longer and wondered how HN frontpage news is determined?