October 2007, during testing. There won't be any Smash Bros. leaks until the end of development. The only people who currently know anything about the game are the developers in Japan and the Treehouse translators in America, neither of whom are going to spoil anything about the game (for obvious reasons). Testers have no sentimental attachment to the work and are more likely to break a nondisclosure agreement.
If only..if only. Although, I doubt I'll believe the information if something were to get leaked. Too many fakes.