What the? According to Joystiq, and then looking at the Smash Bros. site itself, the release date for Super Smash Bros. Brawl has indeed been changed from December 3rd to TBD.

This development comes after news that the Japanese release date has been pushed back to January 24, 2008. Oy!

My guess is that it's the online multiplayer that is still being hammered out. Hey, Nintendo is good at not releasing games until they're ready, so I'm going to trust them for now.