Update: Monster Hunter 3 Ultimate is limited to local multiplayer on 3DS, but has online multiplayer on Wii U. The Wii U and 3DS versions can play together locally as well.
Monster Hunter Tri G is coming to both the Nintendo 3DS and Wii U in North America and Europe next year. Nintendo of America announced the game’s official U.S. title this morning—Monster Hunter 3 Ultimate.
Details from Japan report that the Wii U version of the game will have online play. Monster Hunter 3 Ultimate will launch in the U.S. in March 2013. Both versions of the game will have cross-platform saves and multiplayer.