Bungie's next project will result in a MMO-esque action game in space, according to reports from GDC in San Francisco. Bungie's lead network engineer confirmed the rumours that have been circulated for a while now, but pointed out that it isn't a "World of Warcraft in space." (That's what World of Starcraft is for, amirite?) Exactly what is "MMO" about it isn't really clear, but expect some form of perpetual world at least.
The game has no official title or anything yet (even if "Destiny" has been floating around the rumour mill for a while now) and is the first non-Halo game the studio has released since Halo: Combat Evolved. Of course that was during Bungie's Microsoft-days, these days they are working with Activision.