Software developer jag.gr has recently released 645 Pro, a camera app for the iPhone that includes a number of features aimed at advanced photographers.
645 Pro can capture TIFF images that do not undergo any prior JPEG compression stage, which the developer believes is unique in iPhone camera apps. (They are referring to these files as "developed RAW" TIFF images.)
The app also features real-time shutter speed and aperture readouts, a live histogram, a choice of spot or multi-zone metering, as well as focus, exposure, and white balance lock.
In a retro/niche touch, the app provides five "backs" -- settings for five different medium format aspect ratios from 6 x 4.5 to 6 x 17 and also seven film modes, which simulate Kodachrome and E-6 slide films and what appears to be a generic color negative film and some Ilford black-and-white stocks.