If you rushed home with your copy of Super Smash Bros. Brawl, and were met with disc read errors, you're not alone. Nintendo believes that it's the result of a dirty Wii lense, the same problem that plagued the Japanese release of Smash Bros. Brawl a few months ago.
Super Smash Bros. Brawl is the first double-layer disc released for the Wii, and a little bit of dirt on your Wii's lens can prevent the game from running properly.
Nintendo doesn't want you to try cleaning it yourself, as you run the risk of breaking your console, and may end up being Wii-less.
If you're having issues with your Wii and Super Smash Bros. Brawl, fill out the repair form on Nintendo's website, and they'll do it for you.
The bad news? You'll be Wii-less during the repair, and it's hard to tell how long it will take. The good news? Both the repair and the shipping are free.