ofxiPhone is an addon for OpenFrameworks that allows artists to easily create works for the iPhone in c++. I worked on it with Memo Akten,Lee Byron, Damian Stewart, Zach Lieberman, Theo Watson and Arturo Castro.

Files:

it can be downloaded as a complete package at: http://openframeworks.cc/download

the svn, which I highly recomend you check out the most recent update from is located at: http://code.google.com/p/ofxiphone/

Tutorials:

-My tutorial for ofxiPhone

Memo's excelent tutorials:
-Simple openFrameworks application on iPhone Sample 1
-Developing for iPhone using openFrameworks and ofxiPhone

More classes I have written which have yet to be integrated (incomplete - but working - classes are noted):
(note these all require you to change your main.cpp and testApp.cpp to .mm files)

ofxALSoundPlayer
implementation of openAL for the iphone. Based on Apple's SoundEngine code with some tweaks. Requires the OpenAL.framework framework added to your project.. Go to libs/core/core frameworks/ and right click. Select 'add existing framework' and pick OpenAL.framework.

ofxiPhoneFile
easily write and read files to the documents section of the iPhone. These documents are linked to your app and this area is typically used for writing and reading files related to your app, like preferences.

ofxiPhoneKeyboard
wrapper for the UIKeyboard object. Also a reasonable example on how to wrap any UI element

ofxiPhoneImagePicker
wrapper for the UIImagePicker object. This allows use of the camera in iPhones, as well as the image library in iPhones and iPod touches. It should be noted that saving images the user takes with the camera to the library is unfinished.

ofxiPhoneCoreLocation
wrapper for CoreLocation. Requires the CoreLocation framework to be included in your project. Can load lat/long and altitude data, as well as compass data on devices where this is available

ofxiPhoneProgressIndicator
This is a quick and dirty wrapper for the iPhone Progress Indicator

ofxiPhoneOpenCv
a version of the openCV library compiled for ARM devices. Combining this with the ofxOpenCv by Stefan Hechenberger and Zachary Lieberman should allow openCV use on the iPhone