-By Brian Morrissey, Adweek

U.S. consumers are flocking to use social networks and other participatory venues to the extent that the activity is now mainstream, according to Forrester Research.

The company's polling indicates 2008 has marked significant growth for social media, with a decided majority of users now taking part. A consumer poll done in the second quarter found that 75% of Internet users participate in some form of social media, up from 56% in 2007.

Adoption rates vary by the type of activity. For example, Forrester found large growth in participation among those reading blogs and writing product reviews. "Spectator" rates jumped from 48% to 69%. Likewise, those identifying themselves as "critics" increased from 25% to 37%.

Yet other areas saw more modest increases. Maintaining RSS feeds and tagging Internet content remain far from the norm. Just 19% fell into that "collector" category, up from 12% a year ago.

Rates of content creation have slowed considerably. Those publishing a blog or personal Web page saw incremental growth: 21% versus 18%. In fact, blogging grew just 10%, well behind the 39% growth in starting a social network profile. Still, blogs remain a highly popular form of social media: 48% of respondents said they have read one, a nearly 50% increase from 2007.

In another sign that social media has gone mainstream, Forrester found the participation gap narrowing among age groups, though younger demographics still rate higher. Forrester found 35-44-year-olds increasingly entered the ranks of critics, joiners and spectators.

"The novelty of today's social technologies will eventually wear off, and consumer adoption will plateau as all new media eventually do," Forrester analyst Josh Bernoff writes. "But consumers will expect marketers to continue the relationship they've formed over time and still listen to what they have to say."