Its not idiotic for them to throw in a front facing camera. For all we know, the one showed at WWDC could have been a prototype.
Look at it like this:
iPhone 3G is announced. Hype is going crazy, everybody wants an iPhone. As it gets closer to release, people lose interest and look into other options for phones. July 10th, Apple announces a front facing camera in the iPhone. Hype spikes back to original hype. Everybody and their brother run to the store to impulsively buy a new iPhone.
From June 9th, to July 11th is 32 days. Thats a long time for Apple. A lot hype could be lost by then. Apple's famous "one more thing" could keep the hype high.
My two cents.
P-79