MacRumors.com

Boy Genius Report posts an internal AT&T email to employees limiting vacation requests during the June 15-July 15th timeframe, citing the likely "biggest selling period we have seen in a few years."

To ensure proper staffing during the product launch period, Sales personnel planning to take approved time off are encouraged to schedule their vacations before June 15 or after July 15 to participate in the iPhone launch.

Previously approved vacation will be allowed where voluntary rescheduling is not feasible

No additional vacation requests will be approved during the launch period (6/15 – 7/15).

An earlier report from the same site indicated that AT&T was also planning large iPhone displays for the launch:

Apple iPhone displays will soon be hitting AT&T stores across the country and yes, we got some details! First off, it was relayed to us that many stores will actually have to be rewired because the display demands its own power supply, and even requires a network cable. As far as the size of the iPhone display itself, get this — 7 ft tall, and 3 ft wide! Many stores have already started installing the necessary power systems which means that working displays should be here within the next few weeks.

Apple has stated that the iPhone is on track for a "late June" release.