...interesting, this is something they recommend NOT to do on social media websites:

involving your site in schemes where your content is artificially promoted to the
top of these services.

For a long time Google endorsed viral link building on sites like Digg with no reservations. They figured the wisdom of crowds would naturally prevent undesirable content from becoming popular and getting links. Of course this is because the folks at Google tend to lead sheltered lives, and dont believe people would ever sell votes, links or social media influence for cold hard cash those of us living in the real world know otherwise. After living in denial though they eventually come around, and then start asking everyone to narc on other people, despite it being a really bad karma move.

How long before we see a How to report social media spam section of the google guidelines, and link to a form in webmaster central?

Del.icio.us

Digg

Reddit

Furl