To take it a step further than "test our API and show us the cool thing we could build with it", I think it's also "you young, bright programmers, show us which

To take it a step further than "test our API and show us the cool thing we could build with it", I think it's also "you young, bright programmers, show us which of you is willing to work yourselves to death for whatever arbitrary tasks we assign you". I may be a bit too cynical, but there's some element of that in those sponsored hackathons as well.