Nope, the US won't get anything new in the game, he's confirmed this in at least one interview. There was a massive rumor about downloadable content, which eas leaked from a course that has been right about lots of Nintendo leaks in the past, so lots of people thought it was true. Unfortunately, Sakurai put that to rest.
The English version of the game has been finished for a couple of weeks, the added time before the US release date was in order to produce enough physical copies of the game, as well as for protmoional things (like the Official Nintendo tournaments and the gamestop tournaments).
As for the game, I know that lots of members here are interested in playing online against each other, and I'm working on setting up a way that members here can have ranked matches, etc. I've been talking about it a lot in irc, but if you're not an irc person, let me know here if you're interested.
When the game comes out, I am going to be closing this topic and creating a new Brawl topic (and by I, I mean another moderator most likely, since I probably won't be around for a few days), since this one is pretty old with all the Dojo hype, etc, the new one will be about play experience, etc. I think that makes sense.
To generate discussion: What characters are you guys looking forward to playing? Are you happy with the final roster? Who is following this game competitively? etc