Confirming reports we've heard previously, Bungie announced at GDC today that its next project will be a "massively-multiplayer action game."
While Bungie lead network engineer David Aldridge did reveal that fact, he denied the other description that had been mentioned in the past. According to him, the new MMO will not be "WoW in space," for what that is worth.
The report last month claimed that Bungie's next title would be an MMOFPS named Destiny. That may or may not be accurate; saying that the new game is a "massively-multiplayer action game" doesn't rule out the possibility that it will be a shooter of some sort. For an MMO it makes more sense that that game take place in the third-person where you can see your character and the way you've customized him or her. Of course, we know absolutely nothing about the new game, so that might not even be something you do in Bungie's new game.
Whatever it is, the new MMO will be published by Activision.