When pop diva Britney Spears joined the Twitter social networking/microblogging site in October, some commentators said this could be the beginning of Twitter’s swim into the mainstream. Already, Twitter has been riding the wave into the hearts of journalists and politicians alike — not to mention of the tech-addicted masses.

Even president-elect Barack Obama started tweeting to his Twitter site before the election , and was followed by nearly 105,000 Twitter-ers at the end of October—in fact, his “followers” list grew by 1,000 or so in just one day in October. A month later, after having been elected, he had about 30,000 more followers.

Twitter, which pushes the theme of “What are you doing?” for its posts, is just one of the newcomers to the online social networking scene. Its popularity is proving what the Nilsen/NetRatings Internet market research firm said back in 2006: “Social networking is not a fad that will disappear.”

If the term “social networking” invokes visions of strange websites posted by teenagers on MySpace, you’re behind the times by a few years. While MySpace is still the most-common site for posting everything from baby photos to party play-by-plays, companies big and small are increasingly taking to MySpace, Facebook and other sites as nontraditional marketing venues .

Companies from AT&T to Zappos are part of the trend, and surveys are showing that a large number of consumers expect to receive some form of marketing or customer service via SN sites. In fact, they’re a must-have for anyone trying to market online to Generation Y ; about 85 percent of Gen Y-ers are into social networking, and a survey by Internet Retailer this August showed that nearly 40 percent of responding businesses are marketing on social networking sites, and about a third had a presence on Facebook as well as YouTube.

“Companies are now more and more using Facebook to set up corporate-sponsored sites. I think everybody’s trying different things to see what works — it’s a new realm for companies and marketeers,” says Annie Eissler with the Bainbridge Island-based marketing company Mixtur Interactive.

She says the corporate website is meant for information like annual reports while social networking websites can be more personal and used for marketing messages. “People are looking at them as a way to get to know the company and the people in the company,” she says.

Dell recently launched a “Social Media for Business” site on Facebook that includes brief guides for businesses on how to capitalize on those free websites, including “best practices.” Some of its tips for Twitter include tweeting special offers or discounts to unload excess inventory, questions or ideas to get instant feedback about the company, or real-time updates from industry or company events .

But you don’t have to be a big company to embrace social networking. Local professionals and solo-preneurs, from lawyers and chefs to graphic designers, are harnessing the power of this emerging medium.

“I want to be found easily on the Internet,” says Dan Weedin, a Poulsbo-based executive speech coach and presentation trainer. To be easily found, Weedin, who wears another hat as an insurance consultant, has a presence on Facebook, Twitter, LinkedIn and Biznik, as well as two YouTube channels.

“You have to have a strategy when using these, even if they’re free,” he says. “For me, the strategy is to raise awareness with other business people and potential clients. It’s like branding: ‘Who is Dan Weedin’ and what my services and resources are… It’s also like viral marketing.”

Eissler finds LinkedIn a good online way to network with people she’s already met, and expanding her network through them. Recently, she linked in with a person next to her booth at the West Sound Technology Association annual summit, and then through his network reconnected to someone with whom she once worked in Europe. “For some businesses, the chamber of commerce is great but for our business, we can’t get these kinds of contacts in person,” she says.

Carmel Wieland, a personal trainer from Seabeck and owner of Better Bodies by Carmel, has been on Twitter for going on two years, and says it’s a good way to build relationships. “I know people will buy services from personalities they feel they know, so I use it to get my name and my personality out there so people feel like they know me,” she says.

Biznik, which started out in Seattle, markets itself as a combination of online and face-to-face marketing tool, and many of those using social networking sites prefer it over LinkedIn because Biznik profiles are public and they increase search-engine visibility.

Try Googling, for example, for personal chefs in Gig Harbor, and the name of Sara Myron comes up right at the top. Myron joined Biznik earlier this spring. In business for three years, she uses it to not just network with potential customers but also with other chefs. Recently, she was invited to join an “offline” women’s networking group, after someone found her on Biznik. She likes to use the site to learn about meetings in her area so she can connect with others. “The more people I meet, the better,” she says.

Just like with blogging, you can get carried away with online social networking, and find yourself playing around for hours. That may be one reason why some employers are frowning on the idea of workers tweeting etc it on the company dime, and there are continuous informal discussions on whether Twitter et al should be banned at work.

But just like online shopping that caught on fire in the last decade, social networking is becoming embedded into the modern lifestyle. Sooner or later, as Gen Y and the Digital Natives become the primary decision makers around, Twitter and Facebook are bound to become what Google has — anyone who isn’t Googling these days has missed the train out of the Dark Ages.

“I think going forward, the social networking sites will be more important because some of the traditional ways of reaching customers are getting lost,” says Charles Keating, owner of Keating Consulting Services and treasurer of WSTA. “If you’re looking at a diminished economy and people are working harder to find their customers, you use any tool available.”