We can confirm that on March 22nd, the launch day of Monster Hunter 3 Ultimate for Wii U and Nintendo 3DS, an application named MONSTER HUNTER 3 ULTIMATE Packet Relay Tools for Nintendo 3DS will be made available as a free download on the Nintendo eShop on Wii U.
This application allows players of Monster Hunter 3 Ultimate on Nintendo 3DS to play the game online by using a Wii U console connected to the Internet via the Wii LAN Adapter or Wii U LAN Adapter (to be sold separately). Using this set-up, one Nintendo 3DS system can connect to the Wii U console, and play Monster Hunter 3 Ultimate online with other players.
Please note that while the Wii U console is providing this function for the Nintendo 3DS system, it is not possible to simultaneously use the Wii U console for playing Wii U software or to connect locally to another Nintendo 3DS system. A copy of Monster Hunter 3 Ultimate for Wii U is not required.