Hmmm. I'm in the not-convinced camp on this one, because I'm imagining Mario Party with Wii Sports, which means a fairly vanilla offline affair, which doesn't strike me as all that interesting.
'Course maybe it is totally schweet and I am completely offbase, but at the moment I'm really doubting the hype.
Guess I'll wait for a movie or something first though.
I'd still prefer the old, old rumor of the Nintendo + Sega RPG, where the characters were named Ages and Odnetnin.