Part of the problem is the walled garden affect of Facebook, is there a public API that provides you with links to public posts about a piece of content ? I dou

Part of the problem is the walled garden affect of Facebook, is there a public API that provides you with links to public posts about a piece of content ? I doubt it, although Facebook uses this internally to show me random strangers blathering about various news stories. Twitter might be easier but still not sure if there is something that an API can query to find links to a certain article or piece. I remember back in blogging days there was a ping back functionality that was supposed to do something like this. Usually if I find something interesting in the tech sphere I just find people commenting about it on Hacker News and it's a tight but broad enough community to get good discussion.