Matt Cutts Link Building | Google and Social Bookmarking links

Matt Cutts: Typically, our policy is: a link is a link, is a link; wherever that link’s worth is, that is the worth that we give it. Some people ask about links from DMOZ, links from .edu or links from .gov, and they say: “Isn’t there some sort of boost? Isn’t a link better if it comes from a .edu?” The short answer is: no, it is not. It is just .edu links tend to have higher PageRank, because more people link to .edu’s or .gov’s.

To the best of my knowledge, I do not think we have anything that says social bookmark links are given less weight. Certainly, some sites like del.icio.us and other people, may choose to put individual “nofollows” in and they may choose to take actions to try to prevent spam, but we do not typically say anything like: social bookmarking by itself - give less weight.

Again, straight from Google: “our policy is: a link is a link, is a link”

So yes, we mix in social bookmarking links among the other links that we build for clients. What remains important is initial moderation.

You do not want to bookmark your site 100 times in 48 hours, for instance. People will sell you a large amount of bookmarks and deliver them almost immediately which is a major risk to your website of being penalized by one or more search engines or even being completely deindexed by them.