Rockstar Games and Amazon joined forces to develop a new game feature for Grand Theft Auto 4 that will allow players to download the real-world MP3s of tracks played on the game's radio stations, Yahoo! Games reported.

Built into GTA 4's mobile phone interface, the in-game "ZiT" technology will permit the users to tag a song currently playing on the in-game radio by dialing ZIT-555-0100. They will soon receive a text message detailing the title and artist names.

For those who also sign up for the new Rockstar Games Social Club, an e-mail will then be sent with a link to a custom Amazon.com playlist which features the tracks phoned in. The songs are DRM-free and will be priced in the 89-99¢ Amazon price range. This playlist will store all songs tagged "ZiT," from which you can listen to previews and purchase any of the songs in digital form. However, the service will initially be available only within the U.S.

"Music has long played an integral part of the game playing experience," said Ronn Werre, EVP, EMI Music's Sales, Licensing and Synchronization unit. "We think giving players the ability to identify and buy their favorite tracks from Grand Theft Auto IV's popular radio stations is a great new music discovery tool for fans and an innovative new revenue stream for artists."

Boldly proclaimed by Rockstar as "the biggest in the history of entertainment," the Grand Theft Auto 4 soundtrack consists of more than 150 songs, ranging from popular hit songs from well-known artists to more obscure tracks, such as Electrick Funk's 12-inch treasure "On A Journey" and Elton John's "Street Kids" off his relatively unheralded "Rock of the Westies," as well as some songs from popular artists created exclusively for the soundtrack itself, like "'Vagabond (Liberty City Mix)' by the Greenskeepers and "War is Necessary" from iconic rapper Nas.

Initially scheduled for an October 16, 2007 release, the game will hit the shelves on April 29, and will be the first in the series to be released on the Xbox 360 and Playstation 3.

Meanwhile, Rockstar released the fourth last trailer of GTA IV, entitled Good Lord, What Are You Doing? or Everyone’s A Rat. Check it out here.