Well in what seems like a... well.. I don't know how to put it.
But Sonic and Mario in the same game for the first time ever.
Rivals for the last 16 years.. well not so much the last 5 or so, but eh.
http://uk.wii.ign.com/articles/776/776460p1.html
http://www.sega.com/gamesite/marioandsonic/index.php
Think should be fun in the wii Sports sort of way.