There is not a collision detector built in as of yet.
However during beta lots of folks tried some javascript add-ons to test collision detection mainly with our pinball samples
You could in theory allow an item to interact with another item and then launch a new timeline with your exploding animation similar to the drag and drop example Daniel Morgan posted awhile ago in the forums. See the attached .Hype file.
drag_drop4.hype.zip (22.0 KB)
So combining some javascript and the physics engine and timelines you could get a nice collision method for your work.
Also there is a jQuery collision method that can be edited to work as well.
Look at GameQuery for examples.