Hi all, does anyone know if it's possible to Macro-ly change the name of a layer to it's file name?

If photoshop CS that is. :P

Look up Actions in Photoshop help. You could make an action that changes the bottom (or some other) layer's name to something, its possible you can automatically name it the filename, if you can copy and paste from somewhere. That's the only way I know of to automate it from photoshop, its possible if you write a plugin though, but I know of none which exist.