Smash Bros. Brawl is America's biggest selling game this year
According to this Gamasutra piece, Super Smash Bros. Brawl is the biggest selling game in America so far this year, with 3.5 million units sold.
Mario Kart Wii's in second place (3.4 million) with GTA IV coming in third, with 3.2 million copies sold.
More through there. These figures are taken from Matt Mathews' latest NPD analysis feature.