1. A method, comprising: at a portable electronic device with a touch screen display: displaying on the touch screen display a first user interface for a phone application during a phone call; detecting activation of a menu icon or menu button during the phone call, in response to detecting activation of the menu icon or menu button, replacing the first user interface for the phone application with a menu of application icons including an icon for the phone application and an icon for a non-telephone application; maintaining the phone call while displaying the menu of application icons on the touch screen display; detecting a finger gesture on an application icon in the menu of application icons other than the phone application icon; in response to detecting the finger gesture on the application icon other than the phone application icon, displaying a corresponding application user interface on the touch screen display while continuing to maintain the phone call and modifying the corresponding application user interface to include a switch application icon that is not displayed in the corresponding application user interface when there is no ongoing phone call; detecting a finger gesture on the touch screen display on the switch application icon; and in response to detecting the finger gesture on the switch application icon, replacing display of the corresponding application user interface with the first user interface for the phone application while continuing to maintain the phone call.