I've had the iPhone 4S since late October, and despite my previous reluctance in having such a device, I'm head over heels with it. Well, this might be an exaggeration because some of my friends and peers have really gone "extreme" with its photographic apps, and I'm not.
That said, I do like to use the various apps such as Instagram, Hipstamatic, Snapseed and the like that I have on mine. The lastest to appear is 646 Pro for iPhone whose claim sounds interesting. It claims that the app has been designed for professional and serious amateur photographers, and is the first and only iPhone camera app to give TIFF image files that have no in-app post-processing applied and no JPEG compression.
As for multimedia photographers enamored with the iPhone, here's the iPhone Boom Mic, a small microphone that provides iPhone videos "professional" style sound. The microphone attaches to the iPhone's headphone jack. It's very lightweight, has a broad directional and a super-directional setting for more precisely focused recording.