All of a sudden, linkbacks have become to topic of conversation. It sounds like something really cool and perhaps technical but it's a simple thing that I don't think we need to use. The admins are talking about that now so I can't say for sure but I can explain the idea.
In today's world of search engine rankings, Google uses some formula to calculate a page rank and search results. A huge part of that formula is the number of links that Google detects linking to some site, call it S, and the quality of the sites. Sites with higher page ranks carry more weight when they link somewhere than sites with lower ranks.
So in response to this system, link building has become a huge part of marketing and trying to manipulate Google. Let's say site S posts a link to a page on MHB. Our software picks up on this if someone clicks it and tells us we have an incoming link. If we "linkback", that means we post a link to S on our end. The software add on vBSEO encourages this kind of friendliness but I don't think it's necessary as a rule and it turns links into a pure commodity rather than actually sharing something interesting.
That's my take on it at least. Hope that clears up some questions.