Good Tutorials for a photo app.

GLImageProcessing:
http://developer.apple.com/library/ios/#samplecode/GLImageProcessing/Introduction/Intro.html

AVCam:
http://developer.apple.com/library/ios/#samplecode/AVCam/Introduction/Intro.html

PhotoPicker:
http://developer.apple.com/library/ios/#samplecode/PhotoPicker/Introduction/Intro.html