Yah - just to follow up on what Kareem said, you could imagine sharing tons of programming links on The Shared Web - and it would never bubble up for all your friends who don't follow programming, but for those of your friends who are interested in it - they would get it.
You as a reader of content also get a wider variety of content - and you're encouraged to post as much as you want, and repost lots of content (as that helps us pick out the good content from the bad), and we have various techniques to avoid duplicate posts at the same time. (A Repost counts like an upvote essentially)
In terms of the cheering section, we did mention to friends that we put this up on HackerNews, and to give a shout out if they like the site. Those people in the comments are all real people, who do actually log in daily, and like the site.
We really just wanted to get the word out to the HN community and to get feedback on what works and what doesn't.