Nintendo has had online plans since the NES.

The port on the bottom of the NES? Meant for a modem. Never materialized in the US.
SNES? Same deal. A third-party company filled the void with the XBAND network, but closed 3 years later (this wasn't technically online, but was very innovative and fun.)
Nintendo 64? Modem was part of the 64DD, released only in Japan. Used RandNET. Closed a year later.
GameCube? $50 modem separate purchase. Exactly one game used it.
DS/DS Lite? Just starting to get there.
Wii? Ridiculous System and Friend codes.

The history of Nintendo's online gaming, or lack of, is not a happy point for Nintendo fans. Each system gets promises about online connectivity, and gaming, and it never appears in the end, or ends up a badly neutered, watered-down version.

And Nintendo innovation may come back to hurt them. After the announcement of the WiiU, their stocks dropped. Which may seem familiar because the same thing happened after announcing the Wii, except this time they didn't recover at first. Nintendo's whole thing about the Wii was "bringing people together", even the name was chosen because it was 1. Not a word in Japanese or English, 2. Sounded like "We".

So now they decide to have this tablet-like controller, but due to the limitations in the hardware, only ONE can be used with a system, and they will not be selling them separately (they cost too much.) So they focus on a personal experience, and give the system the ironic name "WiiU."

While I have always loved that Nintendo innovates, I think they may try to innovate too hard this time, and end up with a system that simply won't sell. The people who have been buying the Wii have been the types who don't care too much for graphical power (the majority of the purchasers have been younger families, and older adults) so the increased power of the system isn't likely to appeal to them. With 3 of the 4 people having to use a Wii remote, and only one person getting the new WiiU controller, many people might see it as a non-upgrade over the Wii, and not buy it.

The 3DS has already been failing badly. It was overpriced (the price was based on people's reactions when it was unveiled) has poor battery life, a form-factor which is unattractive to some people, and almost everyone knows a "Lite" version will be coming sooner or later which fixes these problems. They had to drop the price by $80 just to get the thing to start selling again in Japan. (The largest and quickest price drop on a Nintendo system in history.)