Nintendo's going to be a major contributor to the 'E For All' Expo in October.
It is quite possible, then, that if Brawl is not out by that time, it might be the first place to give us a hands-on demo of the game. It may also allow people to buy it ahead of time. That means info leaks are possible.
That's October 19th-21st.
Speaking of conventions, the Austrlian GO3 Expo starts tomorrow and ends on Sunday. Chances of Smash Bros. news? Nil.