Since its launch the Wii U has introduced the Nintendo Network ID and Miiverse, the latter of which was promised for the 3DS when it was revealed just before E3 2012. In its most recent Nintendo Direct broadcast Nintendo confirmed that a December update would introduce the ID and shared eShop funds across the 3DS and Wii U, while also delivering the much-anticipated Miiverse platform to the portable.
As reported last week, extended maintenance has been completed on the Nintendo Network and, as was expected considering the timing, it's paved the way for a new system update on the 3DS; it's available in Europe and also appears to be active in North America, too. You should be prompted to update when opening the 3DS eShop, but if not the process can be kicked off manually in the System Settings.
It's a fairly meaty download, but when complete you'll see a Miiverse icon and the system will prompt you to create a Nintendo Network ID or link your Wii U account. Be very careful to get the details right if unifying your Wii U account with the 3DS, as the portable is limited to just one Nintendo Network ID.
The unified eShop balance is likely to be very welcome, particularly for those that manage funds with top-up cards rather than debit / credit cards. At the time of writing the eShop is failing to open on our 3DS and our credit is yet to show on the Wii U account, so that unification isn't necessarily immediate — some are reporting no such issues — but should appear eventually. Miiverse is, naturally, a big arrival, and is working nicely; we'll be playing around with this update's features to provide you with a full user guide later today.
[Update: There is also an update to the StreetPass Plaza, taking it up to version 3.3. Its purpose appears to be linking the Nintendo Network ID to the app, though at the time of writing it's failing to download on our system, potentially due to busy servers.]
Have you downloaded the system update yet? If so let us know what you think of the changes.