Here are some numbers according to history.
Last year, we got the time of the launch on the 11 of June, however, we got the date 9 days earlier. Either way, by June 18 this time, there should have been a time.
Last year, the data and service plans were announced about 3 days before the iPhone came out. That is why I have a good feeling that Apple is holding off the time for a reason. I don't know exactly, but a reason. I think they might be prolonging the inevitable a little too long.
July 11 is fast approaching, and Apple has to deliver 3 new products almost simultaneously. MobileMe(Which, in theory, could be released before), iPhone 3G, and the iTunes Apps Store. That gives me thought that it will be in midday and not in the middle of the night. I have never seen Apple release a product at midnight. (Recently)