give the x and y of the point of collision between 2 objects.
This is useful especially when you have complex objects or wide objects.
Currently it does give you the x,y but it's the location of the object, which is useless for complex objects and for wide objects you need to do manual calculation to get the actual point of collision

Box2D API:

http://www.box2d.org/manual.html#_Toc258082970 search for: 4.8 Contact Manifolds