A USA Today article reveals that MySpace has now reached 47.3 million members. The Blog Herald also reports that MySpace "is growing by an amazing 160,000 new users a day, according to MediaPost".
USA Today gives a rundown of numbers for SNS sites, c/o comScore Media Metrix. They note that "in the past year, the number of visitors to MySpace (from homes, workplaces and colleges) has skyrocketed, making it the Web’s top social networking site":
MySpace.com
Nov. 2004: 4.9 million
Nov. 2005: 26.7 millionFacebook.com
Nov. 2004: N/A
Nov. 2005: 11.1 millionXanga.com
Nov. 2004: 5.8 million
Nov. 2005: 7.9 millionBebo.com
Nov. 2004: N/A
Nov. 2005: 1.5 millionFriendster.com
Nov. 2004: 966,000
Nov. 2005: 1.5 millionTribe Networks Inc.
Nov. 2004: 62,000
Nov. 2005: 515,000Linkedin.com
Nov. 2004: 123,000
Nov. 2005: 354,188Orkut.com
Nov. 2004: N/A
Nov. 2005: 83,000Source: comScore Media Metrix, a division of comScore Networks, Inc.
For some reason, USA Today didn't include LiveJournal in their chart. According to official stats, LiveJournal currently has 9 million user accounts - but only a little under 2 million are "active". That would put LJ at number 3 or 4 in the above chart.
The demographics of SNS sites are interesting. LiveJournal users are skewed to 16-20 years and are 2/3 female. MySpace is said to be mostly < 22 yrs and general consensus is that it's a younger user base than LJ.
All of these SNS services have a very young user base, so in many ways it's a battle for the hearts and minds of Generation Y and beyond. MySpace may be winning in numbers, but recent controversy shows they can't get complacent.