Also from the Minneapolis-St. Paul Business Journal (emphasis mine):
Nielsen said “member communities” are now at 67 percent participation while e-mail is at 65 percent.
The study found that of Internet users throughout the world, two-thirds visited a social networking site last year. Of those Palo Alto, Calif.-based Facebook is the leader, with visits every month by 3 of every 10 Internet users, the Nielsen study reports.
In fact, Facebook had a 168 percent increase in users, the study said, while Mountain View, Calif.-based LinkedIn had a 137 percent increase.
The biggest growth spurt for Facebook has been in the category of users from 35 to 49 years of age.
I believe it. I volunteer to work with teenagers and they all are social site users who mock my antiquated references to email. That is the generation moving into college and then into the work world. Be prepared for the change is already underway whether you realize it or not.