The SEO community was the victim of an interesting hoax this week when a blogger claimed that Google was about to punish sites that relied on social bookmarking to build links.
Matt Cutts and other Google employees quickly explained that the rumours were false but the issue raised some interesting points.
John Mu, a Google employee, stated that:
"I would not worry too much about a blog post that doesn't seem to exist. That said, keep in mind that PageRank is roughly based on the quantity and quality of the links pointing to a page. Traffic from self-created bookmarks does not really play a role in that, at least not directly.
"If you have great, unique and compelling content then chances are that people will want to refer their friends to it, no matter if they originally found the link to your site on a social bookmarking site or through word of mouth."
The key is that Google wants to count natural links that are editorially given. It doesn't want to count links that site owners create themselves.
If you bookmark your site on Digg or del.icio.us and you are the only person that votes for it then there is no reason the link should help you.
Ideally Google would only count links that became popular or even discount all social bookmarking links altogether.
My takeaway from this is that social bookmarking is a means to get links from blogs - you shouldn't be relying on links from the bookmarking sites themselves.