Social networking is definitely seeing a reshuffling of its top players.
Facebook and Twitter are in, MySpace is out, according to Experian Hitwise.
The Internet monitoring company reported last week that Facebook, the No. 1 social network in the U.S., grew its share of all the visits to social-networking sites from 19 percent in September 2008 year to 58.6 a year later. That's a more than 190 percent increase.
Over the same period, Twitter's share jumped from 0.15 percent to 1.84 percent, and the service now ranks as the fourth largest social network.
Ailing MySpace, which is scurrying to remake itself into an entertainment portal, is still in second place behind Facebook, but scores of users have begun walking away.
According to Hitwise, MySpace can still boast 30 percent of the social-networking market, but the site is in freefall. Last year at this time, MySpace captured 66.8 percent of the market.
MySpace is hunkering down to develop more compelling music and video services, but it needs to emerge quickly from its chrysalis with something attractive to offer.
Once the traffic goes, then content owners--such as the musical acts that promote themselves on the site--may be the next to flee.
Overall, U.S. visits to social networking Web sites rose 62 percent from September 2008 to September 2009, according to Hitwise, which tracks 155 such sites.