Nintendo announced a new firmware update for Nintendo 3DS that's coming next month on today's Nintendo Direct broadcast. The update will introduce Miiverse on Nintendo 3DS and you will also be able to register a Nintendo Network ID on your 3DS - if you already have one for your Wii U you will be able to link the accounts and share funds between the two platforms.
Additionally Nintendo revealed that a Youtube app that will let you see videos on both screens is coming.