Fox Interactive Media today said it would launch a free mobile version of MySpace.com for the wireless application browser browser, doing away with the subscription-fee model in favor of a completely ad-supported social networking portal.

MySpace Mobile — along with other Fox properties AskMen, FoxSports.com, IGN and RottenTomatoes.com — today went live as WAP sites, reached by typing their URLs into the browser. Millennial Media was named as the advertising platform, which will populate the sites with banner and text ads from its mobile-only network of advertisers.

MySpace has had a mobile presence for the last year, launching a premium service with mobile virtual network operator Helio using a specially designed application for the carrier’s data-centric phones. Fox followed up the launch with a deal with Cingular — now AT&T — in December to launch a Java application available to all of its data-capable phones, thus vastly expanding its reach. Last week, it launched a similar application on T-Mobile’s Danger-built Sidekick phones.

All of those services, however, have been premium services with AT&T and T-Mobile charging additional monthly fees for their use and Helio including the portal as part of its data service bundle. The new MySpace site will be free except for data charges incurred from a wireless plan, but it won’t have the functionality of its stand-alone application counterparts. Customers will be able to check messages, friend requests and view their own as well as their friends profiles, but advanced features such as uploading photos will be reserved for the premium services, said John Smelzer, senior vice president for mobile for Fox Interactive.

Fox laid out the two-tiered approach earlier this year at the Mobile Marketing Association conference, detailing plans to bring in revenues from both ad and subscription sources. Today’s launch puts that strategy into action, Smelzer said.

“By creating a simple, standardized WAP site, we can attract a larger audience,” Smelzer said. “But we think there will be both ad revenue streams as well as subscription revenue streams, just as we have customers who want basic mobile functionality on MySpace versus more sophisticated tools.” Smelzer added it would continue to pursue premium content deals with other carriers.

MySpace and the other portals will use a Millennial’s dual-platform approach to populate ads on the site. Millennial uses both a headend and tail-end ad buy platform, serving up ads from a few dozen large advertisers based on impressions, while supplementing those ads with smaller, more audience-tailored ads from a much larger ad marketplace. The dual-pronged approach may seem like a lot, but Paul Palmieri, CEO of Millennial, said MySpace will need it. Millennial expects MySpace to be one the biggest destinations in the mobile world, drawing a major portion of its ad buys. “From a volume perspective, MySpace is going to be a significant contributor,” Palmieri said. “One of the largest online, no question.”