One of the breakout aspects of the Wii U that is uniquely Nintendo is Miiverse which has brought Nintendo fans together in a way never before seen. The service feels like a fun evolution/cross of Twitter and Facebook but more focused. The ability to draw has brought a lot of creativity to the concept while the moderation has managed to keep things friendly and inviting, something that is sorely missing from Xbox Live. Its success has caused fans to beg for an expansion to the service to other devices.
Starting this Spring (April/May), Miiverse will be accessible on smartphones and browsers with 3DS support coming later (Summer/Fall 2013 is likely). Basic Miiverse functionality will be available at first which includes posting comments, drawing and access to various communities. Nintendo is currently taking requests from developers for what they would like to see implemented in future updates to the service. If you are a fan, I recommend checking out the service once it's available for your platform of choice. In an internet full of trolls and negativity, this is something pure and fun without all the BS.