The following list is of Wii titles that have been CONFIRMED for launch. Nintendo has already gone on record saying they are planning on having close to 20 titles at launch. That is still the plan but for now, these are the confirmed titles:

The Legend of Zelda: Twilight Princess
Metroid Prime 3: Corruption
Dragon Quest Swords: The Masked Queen and the Tower of Mirrors
Super Monkey Ball: Banana Blitz
Red Steel
Rayman Raving Rabbits

Source: AMN