Back in June, Nintendo announced that they would release a system update for the Nintendo 3DS that would add a new feature allowing the 3DS to receive StreetPass encounters via Wi-Fi access points. This system update is now available for download.
Once you’ve downloaded the updated, your 3DS will be able to pick up StreetPasses from Nintendo Zone access points. When a 3DS user passes a StreetPass relay point, it will automatically store his StreetPass data temporarily, and then pass it on to the next user that passes by the same relay point.
Nintendo hope that the StreetPass relay feature will boost StreetPassing in the west and encourage more 3DS users to take their systems out with them.