Paws for thought: Dogs have a theory of mind?

In a very simple experiment, Schünemann et al. appear to demonstrate that dogs can attribute thoughts and motivations to humans, distinguishing intentional from unintentional actions. From The Guardian summary of the work:

...A researcher was asked...to pass treats to a dog through a gap in a screen. During the process the researcher tested the dog on three conditions: in one they attempted to offer a treat but “accidentally” dropped it on their side of the screen and said “oops!”, in another, they tried to offer a treat but the gap was blocked. In a third, the researcher offered the treat, but then suddenly withdrew it and said: “Ha ha!”...in all three situations they don’t get the food for some reason...The results, based on analysis of video recordings of 51 dogs, reveal that the dogs waited longer before walking around the screen to get the treat directly in the case of the sudden withdrawal of the morsel than for the other two situations. They were also more likely stop wagging their tail and sit or lie down...the dogs clearly show different behaviour between the different conditions, suggesting that they distinguish intentional actions from unintentional behavior.

There is debate over whether this behavior - distinguishing human behaviors based on their intentions rather than some other cue - meets the level of understanding that qualifies as having a 'theory of Mind.'