Nielsen just released its latest data on the number of unique visitors per social media site. The numbers are staggering:
"Among the top 10 social media sites, Twitter.com was again the fastest growing, increasing 1,928 percent year-over-year, from 1 million unique visitors in June 2008 to 21 million unique visitors in June 2009-making Twitter the fourth most visited member communities site in June.
Facebook continued to lead as the No. 1 U.S. social networking site for the sixth month in a row, with 87.3 million unique visitors in June 2009."