Nintendo, usually the masters of simplicity, don't exactly seem to have gone out of their way to makes things easy with the naming of features on their newest console. Unlike SpotPass before it, however, it's a little bit more obvious what StreetPass is all about, simply from looking at its name, as a mode which echanges data with random strangers, as you pass them in the street.
How to use StreetPass
With your system in sleep mode (basically turned on, and folded shut), and your wireless communication turned on, your system will automatically be engaging in StreetPass mode. In this mode, your console will send information from games you've previously played - and your Mii - to people you meet in the street, as well as doing the same vice versa. On a normal stroll through the town, your 3DS will receive information from anyone you pass, whether it's one of their dogs on Nintendogs, their ghost replay data on Ridge Racer, or something a bit more complex, such as Street Fighter IV's figurine battle, which lets your collection of in-game figures battle it out with people you walk past, automatically.
It's certainly an interesting feature, with some pretty innovative early uses, which will hopefully only get more interesting, and more inventive as time goes on. It's a similar idea to Bark Mode, from the DS's Nintendogs, although this time, it's a lot more advanced. Rather than having to have the game in the slot, your 3DS saves its StreetPass data to an SD card, meaning it'll be transmitting information from multiple games every time you walk past someone, regardless of whether you've got the game in your system, or the last time you played it. Each game has to be individually configured to use StreetPass from their menus, at which point it'll create save data on the SD card. You can transmit data on a maximum of 12 StreePass games at any one time - should you get more than 12 games, you can re-order them, and remove games from the list in the StreetPass management menu in System Settings. Parents who are concerned about their children accessing things that they'd deem inappropriate can also block StreetPass from being accessed by using Parental Controls.
Thankfully being rather forgiving on your battery life, StreetPass mode is an interesting addition to the console, that'll encourage you to keep it on whenever you're out and about. At the very least, you'll probably receive the Miis of people you walk past in the street, which can then be used in the Mii StreetPass Plaza games. It sounds complex, but it's really pretty straightforward once you have the console in your hand. Look out for the green flashing notification LED - when it glows, you've got StreetPass mail!