Nintendo has just launched Nintendo Network ID through a new software update on the 3DS. This means that your 3DS will have an account system that’s very similar to the Wii U. In fact, if you own a Wii U and a 3DS, you can now link both consoles to one Nintendo Network ID which will allow you to use the same funds across both platforms.
Other features include being able to use Miiverse on 3DS just like you would on Wii U and of course continued access to the Nintendo eShop. The key feature of this update is obviously the ability to share a wallet between consoles, this is something that has been requested for some time.
There will no doubt be more features added to enhance the Nintendo Network as time goes on, but my personal request would be that they offer more downloads, like virtual console content, that can be played on both the Wii U and 3DS.