Apple has started preparing special displays for the launch of the iPhone at the company's physical stores.
A picture posted [1] on flickr, shows staff installing a display that has the form of a giant iPhone at one of Apple's New York City store.

Source: flickr [2]
The iPhone will be launched on June the 29th. Both Apple and AT&T expect crowds in their stores for the day of launch.
UDPATE: MacRumors gathers a few more [3] pictures.