Customized kernel and nVidia binary drivers

Hi everybody, I am building custom kernels using "make-kpkg" command - the debian way, everything works great even my nVidia propriatery driver. And this nvidia module confuses me so much. When I build my kernel with standard "make", and install it as it is expected there is no nvidia module in my /usr/lib/kernel-ver directory and not surprisingly simply copying this driver from older kernel to a new one doesn't work as well. I wonder how can this nVidia binary driver still work if I compile my kernel with "make-kpkg"? What this utility does to make it happen?