Maggirus on 27 March 2008
I could be late, but it seems like the size of the character roster is known.
(Famitsu said 24, Nintendo Power 18)
http://revver.com/video/771269/mario-kart-wii-trailer/
According this trailer (1:36) Mario Kart Wii has 24 characters. I could be wrong, but you can hear the speaker say "charakter" (or something like that) and they're showing some drivers.
Someone can translate this video, or what's said at that scene. It looks right.... I guess....
