Pinterest is Now the No. 3 Social Network in the U.S. [STUDY]http://mashable.com/2012/04/06/pinterest-number-3-social-network/?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+Mashable+%28Mashable%29 by slacko • 14 years ago 2 0 14 years agoMAmashable.com