Gaming Examiner just conducted an interview with the Creative Director and Game Director of The Last of Us, and it sheds some light on a number of questions gamers have been asking since the initial trailer. The interview touches on a number of gameplay points, such as the fact that the campaign will not involve coop of any kind, but there will be multiplayer of some sort.
My prediction is some sort of "gang-war" type deal, a la Uncharted or Max Payne 3, with nondescript customizable NPC characters. Since we know Sony is all about online passes, it wouldn't be bonkers to expect one for TLOU. In addition to that revelation, there's also a number of other juicy tidbits located in the interview, mostly relating to the design process.
Most notably, it explains that The Last of Us will only have one ending, but will allow players to learn more about the two main characters through various optional means, such as movie posters in certain areas and similar concepts. Basically, that allows the game to tell a distinct pointed story, yet flesh it out at the same time for those of you who are interested, and encourage multiple playthroughs -- great design in my opinion.
It also explains how the game was inspired by working on Uncharted 2 and watching Planet Earth (amazing!), as well as the fact that it will also employ sneaky camera techniques to provide tension. If you're remotely interested in the game, be sure and check out the interview.
The Last of Us: Interview [Gaming Examiner]