Nokia don't really intend end-users to open up the N8; the Symbian^3 smartphone follows the iPhone's example of using a non-user-swappable battery, and has a sturdy, creak-free chassis as a result. However, lack of manufacturer approval never stopped iFixit from tearing down a new gadget, and so they've taken screwdrivers and the rest to the Finn's finest.
It's made easier by the fact that the N8's industrial design leaves the key Torx screws visible, and even the battery is attached via a clip rather than being soldered into place. That should mean user replacements are actually pretty straightforward, as long as you have the necessary screwdriver.
Meanwhile, once the battery and a few more screws are out, the N8 clamshells open and some of Nokia's design choices become apparent. iFixit has plenty of praise for the "pretty genius" steel mid-plane with its integrated thermal pads and EMI shielding, and the Xenon flash unit is supposedly around the same size as you'd get in a regular digital camera. In fact, they rate it 8 out of 10 for repairability.