This is bad. Very bad.
Take a look at this. The barcode to transact the DS sale in store is actually on the back of the unit itself and scannable through a cellophane window in the DS box. This is bad. This means that Nintendo has the capability to identify the specific unit as it travels through the world.
This could add up to a much more serious privacy violation than unique serial numbers in some CPUs - why? In addition to knowing which unit belongs to which person (If you preordered the DS or bought it with a credit card your identity is irrevocably tied to that unit in a database) - this thing can tell something about your location in physical space!
We know that the DS has the capability to come out of sleep mode to recieve a pictochat message from a nearby unit via an ad-hoc wi-fi connection - therefore we can deduce that the hardware is capable of sending such a message whenever you walk through one of the invisible wireless networks that we urbanites pass through each day. It would be a simple matter to catalog the various travels of a unit day in and day out - and because that unit is tied to you....
Hacking this beautiful beast is imperitive if only to explicitly assert our right to privacy.