You can let up to 12 Nintendo 3DS software titles use StreetPass simultaneously in the settings you are looking at.

Because "nintendogs" was the first software to use Nintendo DS's Tag Mode, "nintendogs+cats" naturally is going to be compatible with StreetPass.  As for the pre-installed software, StreetPass Mii Plaza and Nintendo 3DS Sound are compatible with StreetPass.  Also, some software, which will be launched simultaneously with the hardware or shortly after the launch, will be making use of StreetPass.
If I can pick up some of the examples, Capcom says that, with their "Super Street Fighter IV: 3D Edition" game, the players can choose the figurines they can obtain in the game and form a team with these figurines, which can be automatically exchanged with others through StreetPass.  Then, a battle can take place automatically.  You can not only enjoy seeing the results but also may be able to receive the figurinees depending on the results.
In Bandai Namco's "Ridge Racer 3D", the ghost data can be exchanged through StreetPass, and you can compete with the ghost.
In Tecmo-Koei's "Dead or Alive: Dimensions", the character parameters, which shall be determined by a player's play pattern, shall be exchanged and, as the result, you will receive a challenge from the character, they say.
In Konami's "Pro Evolution Soccer 2011 3D" you can exchange the players and formations that you have registered.  A kind of simulation game is played using these parameters.

The Tag Mode of Nintendo DS was enjoyed by a huge number of people through "Dragon Quest IX."  Now, we are looking forward to the expanded ways to enjoy the new StreetPass function.

When you hear the term "social network," it generally means a service taking advantage of social human relationships through a constantly connected network with smart phones and PCs.
In contrast, Nintendo appreciates real human relationships among people carrying around Nintendo 3DS and enjoying it with others.  In addition, we would like to combine StreetPass, which automatically happens to those who are located in the same place by chance, and SpotPass, which unexpectedly happens to those who pass an access point.  With these features, we hope to make relaxed human relationships composed of a wide range of consumers no matter how actively or not they communicate with others and as a result, to widely spread Nintendo 3DS and further expand the gaming population.