Don't Starve's multiplayer-focused spin-off Don't Starve Together is currently in Early Access. That's a sentence I will no longer be able to utter truthfully on April 21—as Klei has announced that's when DST will release for real.
Don't Starve Together takes the single-player Don't Starve and whacks in the ability to play with other humans. It's been expanded over its Early Access period with Reign of Giants and Caves—two expansions from the original game—although it doesn't sound like the recently released Shipwrecked will be playable with chums any time soon.
Of that, Klei says that "we don’t have any concrete plans right now. Shipwrecked was built without DST in mind, and we’re going to need to evaluate how much is needed if we were going to do this. We would all love to go sailing with our friends!"
If you were worried that the official release of Don't Starve Together means that development is about to stop, don't be. "We get that there’s still a lot more to develop," Klei says in the release date blog post, "from longer play sessions, to better modding tools, to improving the state of PvP and exploring the lore—there’s always more to do than we have hands, but thankfully we’re here for the long haul, as long as you are, too."