A source contacted TUAW to reveal that the new "iPod out" feature included in iPhone OS 4 can be used with the iPod Accessory Protocol in automobiles. The tipster said the application includes strings entitled "IAPSSimpleRemoteCarButtonNotification" and "IAPSSimpleRemoteCarButtonTypeKey."
The source said that the information suggests the iPod out feature "might be used in an Apple-branded car kit, where the user docks his iPhone or iPod touch and gains access to the onboard audio libraries (no video at this time). The car kit could include both a video screen to show the menus and custom physical buttons that would produce the notifications to allow the user to move through those menus and select from them."
The report also noted that the application also has a potential reference to hands-free phone navigation with the string "kCTCallStatusChangeNotification," suggesting the feature could route incoming calls to the handsfree system and allow a driver to answer without touching their iPhone.
Some third-party car kits are already available for the iPhone and iPod touch, though they do not add a great deal of features to the devices. The most high-profile releases were from navigation company TomTom, which released hardware meant to boost the GPS reception of the iPhone, and add GPS capabilities to the iPod touch.
The user also provided a video of what the current interface with the iPod out feature:
The iPod out functionality was one of more than 100 features revealed last week by Apple, when the Cupertino, Calif., company introduced its forthcoming iPhone mobile operating system software update. The first major and likely most anticipated feature introduced was multitasking.