Funny, it's basically a long version on what I wrote earlier on search engines and forums, a very interesting read if you're into marketing and stuff:
Discussion boards are cool again. Find out why Google now prioritizes them and how to foster community and engagement on your niche website.
It all goes down to a new "A" word: authenticity. For all their flaws, when you go to a site like Reddit, you know you're seeing real conversations from real people.
searchengineland.com/forums-google-adapt-444065