Nintendo had that big 3DS update the other week, but do you know what feature was missing? If you were thinking of the promised messaging service, you would be correct! Swapnote, also known as Nintendo Letter Box in Europe, is the eShop application you'll be on the lookout for. It will drop in Euroland on Thursday and will probably appear everywhere else on the same day.
As you can see in the video, it operates a lot like PictoChat on the DS, only now you can add photos and sound clips to your messages. Oh, and the messages can be sent via StreetPass and SpotPass, so there you go. Chew on that.
[eShop] Swapnote/Nintendo Letter Box - First Look [YouTube]