It won't be a huge function as not to isolate people that can't get streetpasses so easily. My guess is something to do with finding items or exp for levelling similar to the pokewalker, obviously with some changes of course.
Just dodge U-1, keep dodging! Pokemon Black 2 - 0562 4704 4442
There is so many possibilities. One that could work is info of peoples current team sent so that they can battle that team. Only problem besides nerds raging over the team info being sent is the level difference early game.