In response to "multitasking", it doesn't really seem like it. It seems more like running multiple programs, but only one is ever really active (meaning the rest are "frozen"), whereas multitasking has multiple programs running at the same time with all active "in real time". For example, if you had Nintendogs running, then you go do something else on the 3DS, yet your pups/kittens are still playing around "in the background", or, if you are running the internet browser while it's also playing music.
Now, it may do actual multitasking, as the video had the pup licking just as the Home button was pressed, and after returning to the game, the dog was in a different place, but that could have been editing of the video (since it is a commercial that is a compilation of separate recorded videos).
I'm not trying to be negative. I'm just wanting to know what's really going on. I still want the 3DS. While the $250 USD seems like a bit much, at least it's not being released right away, giving me some time to save some more money than I assumed I would pay, as I'd like to get a few more games that they showed.