Update 2: Don't Starve Together is now available for PC/Mac/Linux, on the PlayStation 4, and Xbox One.
Update: More information about development can be found on the Don't Starve Together Progress Report forum post.
By design, Don't Starve is really focused on being alone, everything wanting to kill you, and fending for yourself. We feel pretty strongly that having the safety net of other players or even competitive interactions with them, would change the mood of the world a lot. You can find more info about this in our past roadmap discussion here: http://forums.kleientertainment.com/index.php?/topic/4078-multiplayer/
That being said, we’re not against multiplayer, it was a decision made to ensure we could deliver on our original promise. In fact, we discussed it a lot in the early stages of the game. We just decided that a good single player game was going to be our focus. Once we decided on this, we did decide to add mod support for the PC/Mac/Linux versions and made it possible for people to attempt their own run at it. Who knows what the community will come up with down the road.