Yeah, it's Infected. I've never even played the game, but I was intrigued by the idea of potentially infecting millions (or thousands in the PSPs case...) of systems with a virus that was not only unique to me, but trackable as well.
Hopefully there are developers out there who think like UncleBob, because this would be awesome with StreetPass.
It could even be done with a little more complexity, like if in Animal Crossing 3D you can design your own furniture that through StreetPass shows up in other people stores. Not only could you see how many different systems your furniture has made it onto, but how many people actually bought it. That idea could of course be expanded into other games that allow you design your own characters...
Which makes me think of Miis, what if every system you pass is tagged with your Mii for Mii parades? If each system tags a StreetPass system with not only your Mii, but 5 other ones randomly selected from StreetPass Miis, it would be even cooler if your Mii made it across the ocean, because it would be based on not only random encounter, but random selection thereafter.
Which actually makes me think of something else; how much information can the 3DS transfer between two people simply passing each other on the street?
Without knowing what kind of radio is used for StreetPass, it would have to be pretty fast to transfer more than one Mii considering the data of the 3D Mii itself, along with name, favorite color, and location. Location would be cool because if your system were to get populated with Miis they could show up on a world map of where they originated from.
Hopefully the 3DS has at least 6GB of internal storage. From Iwata saying they want to push content onto users without them doing anything to get it, Nintendo should include a significant amount of storage.