Thunk has introduced its new Appstand accessory for the iPhone 3G and iPhone 3GS. Appstand is a unique stand for the iPhone that places the device in the center of a mat and frame combination, in effect turning the iPhone into a digital picture frame. Users have full access to all ports and controls while their devices are in the frame; other features include interchangeable Appmats, a spring-loaded stand offering four distinct viewing angles, and…