Nintendo has taken the unusual step of revealing some of Super Mario 3D Land's post-game content within their latest "Iwata Asks" roundtable column. You can watch the following video to see the unlockables but if you don't want to get spoiled, you must skip from 1:50 to 2:45 and 5:40 to 6:10.
Super Mario 3D Land's StreetPass feature unlocks quick mini-challenges for players to complete. Finish the task and you can claim some coins, power-ups, and maybe even an extra life to help with Mario's adventure.
3DS owners can pick up Super Mario 3D Land on November 13.