As promised in last month's Nintendo Direct, a 3DS system update has been released which adds Miiverse and Nintendo Network integration to the system.
Miiverse works as it does on the Wii U, namely you can post your thoughts about games into specific communities, add screenshots or draw messages. A nice feature for those who are on the go is the ability to "save" Miiverse posts whilst offline, for them to be immediately uploaded when your system reconnects to the Internet.
Also included is Nintendo Network intergration, so if you have a NNID already, you can link the same one (and be careful, it's only one) to your 3DS, pooling any outstanding money and purchase history between the two systems, as well as the same Miiverse account between both systems. Hopefully this is a big step towards removing pesky friend codes for good.
Other interesting things added in the update are the requirement to press both L and R to activate the 3DS camera, making it less likely to open by accident, and also the ability to do a 3DS system transfer as many times as you want (the previous limit was five).
To update your 3DS, simply go into the System Settings then select System Update.