Users of such social bookmarking communities submit links to items on the Internet, often entries on blogs. If you get enough people submitting a link to a post on your blog to one of these social bookmarking sites, you receive a spike in traffic.
If you’re like most bloggers like me, don’t get carried away with these sites. One, it’s highly unlikely that you’ll get enough members of these communities to link to one of your blog posts to draw traffic to your blog. Even if you do get a spike in traffic by links to your site, and again it’s very unlikely, the people checking out the post will be gawkers. They’re not your target audience.
Second, these sites can create a lot of buzz and, like the article says, huge traffic without a lot of thought or work going into what they mean as a real business model that can benefit you as a blog publisher. Such sites can be run by one or two employees and/or contractors who create a buzz by people thinking it’s cool to have their blog post socially bookmarked by lots of people. This quick traffic payoff on their sites results in big ad revenues for the social bookmarking site owners.
Such sites are an interesting phenomena, but as a blog publisher don’t get carried away with them.