I personally think this is a great move on nintendos part, one because its another new form of gaming(if we can call it that) and two because of all the extra apps this can be used for.
On the down side though, i think it would have been a good idea if the camera was able to rotate through 180 degrees, then they could have adopted game ideas such as this
http://www.toyspring.com and the camera could have also been used to do normal camera functions.
Another idea would have been for the camera to be spring loaded so when not being used the camera could have been tucked away out of sight and with one quick press it would pop out of the side ready to use.
I think if nintendo were to redesign the DS again, they would add a built in camera and if every piece of hardware had the function built in the game developers would incorporate this into their software. But being as the price set in japan is only £20(GBP) i think we can safely say alot of DS owners will opt to buy this add-on, and if the majority of people own this neat piece of kit, theres no reason why game developers wouldn't start adding some sort of use for it in game if the expansion pak was recognised.
Plus, this also adds a camera function to Wii now, which who knows what weird and wonderful ideas this could be used for. I for one am sold on this idea and prey for a worldwide release, here looking at you ninty!!!