Preview at WWDC likely in June, followed by September launch.
'iPhone 5' Headphone Jack and Earpiece Component Surfaces
If the new part is indeed legitimate, it does represent a significant departure from the component organization in the current iPhone. In the iPhone 4 and 4S, the headphone jack, volume buttons, and mute switch are grouped together on a single component, while this new part associates the headphone jack with the earpiece speaker and Wi-Fi cabling.
It is not terribly unusual for Apple to tweak the organization of components, and the new part leak offers essentially no information on any potential changes to the device's form factor, but with part leaks beginning to accelerate it may not be long before more substantial parts begin showing up.
Update: The center feature of the part appears to be more reminiscent of the dock connector rather than the earpiece, suggesting that the headphone jack may be moving to the bottom of the next-generation iPhone, as has been the arrangement in the iPod touch.