This seemed to be missed in a different thread, so I'm starting a new one...
This is a big hidden thing and I'm surprised Nintendo wouldn't mention it. I mean, they had to know that people were going to figure it out, of course at the same time, they were probably hoping you would to help bring up the hype.
Everyone should check parental controls as well. I read over on infendo.com that there is a new entry to allow online user-to-user communication. Whether this is text or voice communication or both remains to be seen but I am beginning to wonder if this is part of what we'll see as the big September surprise.
Based on this update and the "hidden" things people are finding, the September update is going to be online communication related and will be useful in Mario Kart, among other games. This is update will also occur before Brawl is released, so we might be seeing some sort of communication in that game.
EDIT: Another thought. This might only mean that a text chat channel is coming.