Nintendo Working on Cartridge to allow 3DS to Wii U Connectivity

January 5, 2013 - Wii U - Rumor
Source Says: We've known for a while that Nintendo is planning 3DS to Wii U connectivity (that's been their plan all along with Smash Bros.), but apparently their implementation will involve a special kind of game cartridge.

Patent mockups for the cartridge (featured after the jump) show the cart as being rather bulky; it sticks out of the system like the Action Replay cartridges did on the DS. However, Nintendo will hopefully make the final version of the cartridge a tad less cumbersome.
Source: zeldainformer.com