It should, I thought that too, but I added a box collider 2d to the character sprite and to a a building on the sprite map. But they don't "colide", it passes right by it. That's why i was thinking it should be because of the z axis, im using the 2d view from unity4.3.
And doenst 2dtk have a way to generate coliders on its own?
Sorry for all the noob questions, but I just started using 2dtk