Much like the Magic Trackpad, there isn't much to see inside the new shuffle. The guys admit that getting the shuffle apart wasn't easy. "It took us a good half hour of prying and heat-gunning to open the little guy." The front and back cases were glued and press-fit together. It's a solid little device.
Inside, the battery and logic board live side-by-side in cozy quarters. In fact, they're soldered together (so no user-serviceable battery in the shuffle). Once the connecting ribbon has been removed, you can pop the board's retaining clip and the lone screw holding it in place, removing it and the battery as a single unit. Finally, four little screws keep the click wheel in place.
iFixit shares some other information on the battery, board, and probable dates of manufacture in their article, so go and read it. We suspect, as they do, that these teardowns will only get harder as Apple's hardware continues to shrink.