iFixit has posted the first disassembly photos of the new fourth-generation iPod nano and second-generation iPod touch. They found the nano 4G’s internal design to be quite similar to that of the nano 2G, with removable caps on the top and bottom, which offer access to tiny screws which must be removed in order to slide out the actual components.
The glass screen cover is separate from the metal casing, and is only held in place by the internal components. The main processor appears to be an Apple-branded ARM processor manufactured by Samsung.
In their disassembly of the iPod touch 2G, iFixit found a particularly interesting component. The new touch sports a Broadcom BCM4325 wireless communicaitons chip with both Bluetooth and Wi-Fi support.