According to EB Games and GameStop (Who just happen to be releasing a "Wii bundle pack" on Thursday) there will only be enough Wii's and copies of Twilight Princess at launch to supply those who pre-ordered on the 13th.
My question to you is: Who do you trust? I think EB/GameStop was counting on there being a limited supply of Wii's and is hoping that those who want one are dumb enough to only pay attention to their site. After all, my roommate went to EB the night GRAW on 360 came out and was told that that EB ran out and wouldn't get any more in for at least a week but then when we went to Best Buy and Wal-Mart they had tons of copies.
Same with Final Fantasy XII. The location that I pre-ordered the regular version at ran out of those but they had plenty of the "Limited edition" $60 version (They still do if you don't feel like hassling eBay

I hope this is another situation where it's all corporate BS about pre-ordering because I really don't feel like spending a Sunday driving all over the greater Sacramento area looking for a Wii.