Just to play devil’s advocate-
Current iPhones could be unavailable to simply launch the iPhone 2.0 software. Apple probably wouldn’t want to sell any iPhones with the1.4 old software to avoid confusion and unhappy consumers wondering why their brand new iPhones don’t have the advertised features.
AT&T employees being unable to take vacation could be due to any amount of variables. And if it was to avoid employee shortages during heavy business, they could easily hire temp staff like most malls do during the holidays.
If the brown boxes have already arrived, you can bet money they don’t have iPhones in them. No way Apple would send the iPhones this early. There’s got to be one employee curious enough to risk his job and open a box and leak the info. Also- Apple usually only ships devices the night before the launch.
Apple usually upgrades on an 18-month schedule, not yearly.
And on top of it all, this is a developers conference, not Macworld- they would most likely announce new software, not hardware. (Imagine how you would feel as a developer knowing you spent the last 6 months developing for a platform that is announced to be obsolete at the very conference you’ve been preparing for?)
That being said, I still hope the 3G iPhone is released!