The crates in 0.2.3 don't have that turned on yet I think
By the way, the snails can't normally be thrown around! It was just for this test. However, being throwable or pushable is a property of each monster type that can be set in the monster designer.
I have made one change to the existing monsters though for 0.2.4 -- they can all now carry anything that lands on them. For example, if a piece of fruit pops out of a monster and lands on a tinymon's head, he'll carry it around until it gets bumped off. The player can also stand on monsters' heads, but it causes damage.