We were working on an iPhone app recently and added a Settings.bundle to allow the user to set their preferences as described here and here. However whenever we ran the app either on the device or on the simulator the settings simply would not appear in the iPhone's settings.
After much digging around and many hours banging heads on walls we finally tracked it down. Settings bundles are only added to the phone the first time the application is installed. If you've worked on an application and deployed it to your development device or simulator before adding the settings.bundle to your XCode project then subsequent build and runs won't add the settings unless you remove the app from the device or simulator in the usual way. i.e by pressing and holding the app icon and removing it when it starts shaking.
The next time you deploy to the device or simulator the settings should be present.
We hope this helps someone.