Denver Business Journal - by Silicon Valley / San Jose Business Journal
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, Facebook is the leader, with visits every month by three of every 10 Internet users, the Nielsen study reports.
In fact, Facebook had a 168 percent increase in users, the study said, while 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.