It works like this: You hear a song you like, you'll call an in-game service called "ZiT" on your mobile phone to mark it. You'll get a text message with the song and artist name, as well as an email if you're a member of the Rockstar Social Club. Said email will contain a direct link to download the song from Amazon's music site for $0.89 to $0.99. What's more, there's no DRM, so you can do whatever you like with them.
While we're usually not a big fan of extra ways to monetize games, this actually seems like a pretty ingenious way to integrate the service. This is pure conjecture, but wouldn't it be interesting if the songs in-game (and available for purchase) continued to be updated? ... That Rock Band money has to be pretty hard to ignore.
