Unique visitors to LinkedIn's professional social network reached an all-time high of 33.9 million in June, surpassing MySpace for the most active social network following Facebook. The move comes as no surprise given the recent fortunes of both sites; LinkedIn receiving booming traffic following its successful IPO in May and MySpace being sold for $35 million, $545 million less than what NewsCorp paid for the site in 2005.
Twitter rides in close behind both sites with 30.6 million UVs in June, the site's first month over 30 million UVs. Twitter gained an additional 3 million more UVs from May to June, and recent private financing has pushed the site's value to $7 billion.
Facebook still holds a commanding lead over competing social networks, reaching an all-time high of 160.8 million unique visitors in the U.S. this June. CEO Mark Zuckerberg also confirmed that Facebook has crossed the 750 million user mark.