It has been widely reported, based on Steve Jobs' comment at the 2007 WWDC, that the Apple iPhone will go on sale on Apple's Online Store at 6pm. However, due to the lack of timezone information and a "questionable tone" in Jobs' delivery, speculation ensued as to whether or not the six o'clock time was more of a joke than a reality. Additionally, there was no information on whether the 6pm time also applied to Apple (AAPL) and AT&T (T) retail outlets.
Now, based on an alleged AT&T internal memo published by MacRumors, it is looking more likely that Jobs was being serious about the 6pm release time. The memo reportedly states,
"The iPhone will go on sale on at AT&T retail stores June 29 at 6 p.m. local time in each market."
Presumably, if the 6pm sale time applies to Apple's online store and AT&T retail outlets, it would also apply to Apple's retail stores. Though it is hard to imagine employees at AT&T and Apple retail stores spending an entire business day, leading up to the 6pm release time, dealing with clamoring iPhone hopefuls - for now, this seems like the most likely scenario.