MySpace, which has deals with Helio and Cingular, will expand more..this story has some good details (the Helio deal was an exclusive one, but short term..not sure how long). Among the plans: MySpace plans to make its mobile features available through all major U.S. carriers by early 2007. If MySpace has its way, the network’s mobile applications will come preloaded onto all mobile phones sold, becoming as integral a wireless handset feature as an alarm clock, calendar, or mobile e-mail, the company hopes, though that may be wishful thinking.
Some more details on other social networking efforts like Dodgeball (bought by Google), Facebook, and Rabble, among others.