iTunesArtwork is 512x512 image that you include for iTunes' benefit. You can either stick it in the .ipa (beside Payload/) or in the .app itself; sticking it into the .app might have benefits (it's copied to the device, so iTunes can copy it back off later. But I'm not sure abut this.)
CFBundleIconFile should point to a 59x59 PNG image. The default name is Icon.png. On iOS 4 and above, you should additionally be using CFBundleIconFiles to get high-res images.
I just name my images Icon.png, Icon-72.png, [email protected], and don't bother including the keys in Info.plist (I originally did this because iTunes Connect rejected CFBundleIconFiles for apps compiled against 3.1.3, and we didn't have time to implement all the OS 4 fixes before release).