KineticJS - Shape.setPosition();

Question

I'm having a bit of trouble playing around with KineticJS.

As you can see from my fiddle, I am able to access the Shape object (box) inside of my drop event, to get the x,y coordinates, and I'm performing math on them to get the new coordinates I want to 'snap' the shape to, but I can't figure out how on earth to set the position and redraw the box.

The docs are sparse, at best:

http://www.kineticjs.com/api-docs.php (See Shape.setPosition( x, y))

Has anyone here messed with this library yet?

EDIT: My now working fiddle: http://jsfiddle.net/Programmer/m4MZk/