We received pictures from an "X-Scene friend" of the 4GB internal memory in the new Xbox 360 'S' 4GB model. Unlike the old 'Arcade' units the memory is no longer located directly on the motherboard, but instead Microsoft uses a small addon-on PCB with a 4GB flash memory unit [3.2GB usable]. This probably makes production easier (afaik) as all motherboards are now exactly the same ... for the 4GB model they add the internal memory pcb-addon, for the 250GB unit they add the internal HDD.
As always, hit the pictures of high-res


I also added a picture of the Xbox360 'S' 250GB and Xbox360 'S' 4GB next to each other so you can see the glossy vs matte finish of both units. This hasn't been covered much, but the 4GB model has a matte finish (vs glossy) and black borders (vs silver for the 250GB model). Which look do you prefer?