According to an unnamed customer service manager at Cingular, Apple will release the iPhone on June 11.

Of course, this is not set in stone and could change as both Apple and AT&T might have reasons for the release to slip past this date. Cingular normally updates their website on Sunday evening and June 11th is a Monday. It should also be noted that June 11th marks the start of Apple's Worldwide Developers Conference. Steve Jobs will no doubt grace the stage at WWDC and announcing the immediate availability of the iPhone is sure to generate excitement around the conference. Apple will also use WWDC to focus on Leopard, the next generation operating system scheduled for release sometime in the second quarter of 2007.

Thanks CNET!