9to5 Mac has found references to face detection APIs in the current developer build of iOS 5. The iOS 5-exclusive APIs include CIFaceFeature for identifying a the mouth and eyes in an image of a face. Additionally, CIDetector is a resource within the OS meant to process images for the purposes of face detection. Further iOS spelunking turned up hasLeftEyePosition, hasRightEyePosition, hasMouthPosition, leftEyePosition, rightEyePosition and mouthPosition.
Either Apple is building a Cylon Resurrection Ship or iOS 5 will offer some cool face detection options to developers. In either case, it seems