INSIDE FACEBOOK — Facebook has continued its US surge, according to Hitwise, having grown its market share from 55.2% of all social networks in August to 58.6% last month. That’s a a 194 percent increase over September, 2008, when it had 19.9% of the market. Other social networks also saw some meaningful changes. MySpace dropped from 33.0% in August to 30.2% last month, while Twitter fell from 1.95% to 1.84%. The report’s data on Facebook roughly matches up with our own data about the site, showing that it grew 8.6% to 88.3 million monthly active users in September...

A year ago we modeled out the true value of various social networks based on the idea that users in high-value online advertising markets like Japan, the UK and the U.S. were worth more (financially speaking) than those in lower value online advertising markets. Facebook had recently become the largest worldwide social network in terms of users, but based on our model MySpace was still by far the most valuable social network. We’ve now remodeled social network valuations based on current user numbers and Facebook’s most recent $10 billion valuation. The results are dramatically different...

Facebook users just don't seem to be as young as they used to be. And they're going to the social-networking site a lot more often. A new report from traffic tracker Hitwise shows that U.S. visits to Facebook grew 149 percent in February compared with the same month a year earlier. That pushed Facebook's market share among folks in the United States visiting social-networking Web sites to 36 percent last month, versus 14 percent in February 2008...

Tagged Inc. announced today the company has raised $5 million in venture debt. Led by Horizon Technology Finance and Leader Ventures, the new funding will enable the company to accelerate its growth and expand the services and features of its social discovery site Tagged.com...

Nielsen Online’s September results for the top social networking sites include some familiar names - Myspace.com continues to lead the pack, followed by Facebook and Classmates.com. What is interesting is that nearly half of the biggest social networking sites are also among the fastest growing - and they are all most popular (when ranked by composition index) among age groups over 25...