Battlefield 3's first DLC offering - Back to Karkand - is live on PlayStation Network now, and free to play for all users who purchased a Limited Edition copy of the game.
At the moment, there's a slight bug with getting into a match on Back to Karkand maps but EA is working to get the issue fixed asap. Essentially what is going on right now is when you go to select a Back to Karkand map in the Server Browser, you will only be able to get into the original maps that shipped on-disc. To resolve this, simply use the Quick Match feature and you'll be tearing it up on Wake Island within minutes.
Speak of Wake Island, the team at DICE also released the video above which features footage of Wake Island captured on a PlayStation 3 console. Wake Island is one of four retro Battlefield 2 maps that have been reworked for Battlefield 3 and the Frostbite 2.0 game engine.
Check out http://www.enterbf3.com/ for more information on Battlefield 3.