You guys sound like delusional idiots!
Apple HAS confirmed a July 11th release for 2.0. There's no speculating, when a press release says "... on July 11th" then that means it's going to be available starting on the 11th, if they meant earlier than July 11th they would say "... by July 11th". When they say on it means it's going to be released that day, in this case, July 11th, 2008.
Mark my words, they are not launching it earlier. It's so simple.
The complexity is in time zones... July 11th in which country?
1PM on July 11 in Sydney would be 8PM on July 10th in Cupertino.
An iTunes update will be required for iPhone 3G. Since the App Store is such a promoted iPhone 3G feature, it will most likely be up when the first iPhone 3G's go on sale.
Releasing the 2.0 update before or at the same time as the first iPhone 3Gs go on sale (Thursday night in the U.S.) is a great opportunity for Apple to allow everyone to get the App Store at the same time vs Cupertino and previous iPhone owners being over half a day late...