First of all Drclaw, comparing SSBB to wiiplay is no where near accurate... Do you honestly think they print the same amount of copies for every single game?
The reason Halo 3 was not sold out anywhere and has been shelves since the release is because it was the most anticipated game of the year.
SSBB, being the most anticipated game of quarter 1 08, will be covering the shelves of game stores for ATLEAST a FEW days if not a WEEK or so.
That being said here's a couple of good reasons to
WAIT to preorder.
1. Your selected store may not have it until the day after release.
2. Your selected store may not have a midnight release.
3. Your selected store may not have givaways.
I, NEVER IN MY ENTIRE LIFE, have ever found major game to be sold out on opening day.
And unless Brawl is literally the embodiment of the second coming(however close that statement is to the truth

) I doubt my streak will change.
Get up at 9:00 and check your local gaming store, and I guarentee there will be a copy just for you .