According to the statement, Nintendo has received complaints from Smash Bros. Brawl buyers of the Wii being unable to read their newly bought disc, or of videos chopping up during playback. These users claim to have had no such problems with past games.
Nintendo has come to the conclusion that the problem has to do with dust and tobacco building up on Wii laser units. This effects Smash Bros. Brawl while leaving other titles unaffected because the new fighter uses a dual layer DVD, which is apparently more sensitive to a dirty lens.
The problem can be fixed by simply cleaning the Wii drive lens. This is something that the masses are apparently incapable of doing, so the Nintendo has decided to clean Wii units that are sent to them, free of charge.
Nicely, shipping is free! Smoking is (at least now) a lot more popular in Japan than in the U.S., so hopefully this won’t be an issue when SSBB ships in the U.S. If not, at least we’ll know the issue.