Much like Boyd (my boss) says on the XNA Team Blog, I am pretty surprised we're here today and our announcement hasn't been leaked yet. Even if it was now, we're half of a day away, so it probably wouldn't matter anyway.
No, this doesn't mean i'm leaking it now. :p
Although a decent number of observant people have already found things.
I can only hope everyone is as excited as I am after these next couple days. =)