The first DLC pack, called the Abandoned Territories Map Pack is, as the name suggests, a map pack for the game's multiplayer component. There are four maps in total - Suburbs, Bus Depot, Hometown and Bookstore. Another map pack is also due to be released in 2014.
The final piece of DLC announced today is, fortunately, story driven, and set to release either late this year or early next year. Here's what Eric had to say about it:
"This is an ambitious story with strong ties into the narrative of The Last of Us. We just wrapped up a long casting process for a new character, and we’re starting our performance capture shoot next week."
Naughty Dog are also adding 60 additional head items for Season Pass purchasers. The Season Pass is available for $19.99.