There will be chests found in dungeons and environment of Diablo III, just like the previous games, but it seems likely that they will no longer be locked. Bashiok said this about chests: [1]
- There have been a few discussions about chests, what they meant in the previous game, and what they'll mean in Diablo III. Currently there are no locked chests, and it's not something we're looking to reintroduce for now. We have discussed varying chest quality and types, adding randomness not only to the appearance of a chest but also the value of items it may drop or possibly specifically what types of items it's guaranteed to drop. Mix it up a bit and make finding a chest exciting, but make finding a special chest something even rarer and more exciting. It could certainly make exploring the entire floor of a dungeon more compelling before moving on.