Social networking sites have grown from a niche market for teenagers and college students to a bona fide phenomenon with Facebook claiming more than 140 million active users and the 25 and older age group being the fastest growing demographic. Search Engine Watch’s Mark Jackson says some of these sites may even be beneficial to SEO.

Jackson says that while Facebook is the most popular of the social networks, it’s not going to help SEO that much because a link on a Facebook profile includes a “no follow” tag which doesn’t give a company’s website much value.

On the other hand, LinkedIn, which is a business-to-business social network allows users to ad a link to their website and to describe the site which allows them to use “SEO friendly” wording.

Digg is a little bit different from the other social networking sites, but Jackson says it can help with SEO by adding links. Also, if a company’s employees have Digg accounts, they can add the company’s link to get more interior pages within the site.

MySpace is the site that started the whole social networking revolution, but it’s lost its luster recently as other sites have risen up. Jackson says MySpace won’t really help with SEO, but it may improve traffic – making it an important site.

Earlier this month eMarketer reduced its expectations for social networking marketing in the new year. The company now forecasts $1.3 billion to be spent in 2009 – a reduction of the $1.4 billion predicted in May.

Katherine Griwert is Brafton's Marketing Director. She's practiced content marketing, SEO and social marketing for over five years, and her enthusiasm for new media has even deeper roots. Katherine holds a degree in American Studies from Boston College, and her writing is featured in a number of web publications.