While Nintendo 3DS systems can communicate and exchange StreetPass data around the world, you cannot wirelessly share game data with a system from a different region. Download play is also region locked.
Download play beams a portion of a game to another handheld, usually for multiplayer sessions. This way someone who doesn’t have a particular title can still play with a friend. I tried to set up a wireless battle in Star Fox 64 3D between my US region 3DS and my Japan region system and the two units wouldn’t connect. The receiving unit could not find any software.
Just a little heads up for future importers – if you get a system from another region you won’t be able to use download play either. Download play worked between regions with the regular Nintendo DS. I suppose it makes sense since a region lock was said to be implemented for parental controls and download play games could have ratings (CERO, ESRB, PEGI) tied into the download, but it’s still a bummer that you need everyone to have the same region 3DS just for a multiplayer game.