A new update for the Nintendo 3DS gives us access to the Miiverse and the ability to enable Nintendo Network ID functionality on our handheld systems.
3DS owners can now register a NNID to their 3DS systems or use their current Wii U NNID to combine eShop balances and Wish Lists. NNIDs are now required to download free content from the eShop, such as demos, so it's advantageous to register one, regardless of whether or not you own multiple NIntendo systems.
Players can now join the Miiverse on their 3DS systems as well. This service allows fans to connect with other players around the globe. You can talk to others, give them your sagely advice about certain games and even share images with each other. Just keep in mind that you'll need a NNID in order to share your comments or images.
For those of you without access to broadband internet, there's an offline mode for the Miiverse. You can prepare up to three posts that will be send out as soon as you connect to WiFi.
For more information on the update, you can go here.