Nintendo is going to speed up the Wii U's notoriously slow load times for games and menus with two system updates, one in the spring that will also add the Virtual Console eShop, and another in the summer.
The company is also working on some improvements to their Miiverse online forums, including filters that will tame the chaotic mass of information and the ability to create user communities.
This spring you will be able to access the Miiverse on your smartphone. The phone version of the Miiverse will at first be browser based, but eventually Nintendo will create a special Miiverse app. Since it's browser-based, one would think you could also access the Miiverse from a PC, but Nintendo didn't say one way or the other. (UPDATE: Miiverse will be available on pretty much anything with a browser.)
Via Nintendo Direct