In an iPhone app I'm working on, the user needs to enter some configuration via the settings application before my app will be able to connect to a server and run. Right now when the user first launches my app, I display an alert explaining that the user should go to settings, enter the config details and then relaunch, but this isn't ideal.
Unfortunately there's no way for me to provide sensible defaults for this app, the server host names, user accounts etc. will vary for each user. I think the best I can hope for is to show an alert explaining that some configuration needs to be entered via settings, and provide a "Take me there..." button that will open settings and then open the section in settings for my app. If that's not possible, opening settings is better than nothing.
I vaguely remember that the iPhone jailbreaking people had figured out a way to launch settings or other apps via a funny URL or phone number in the Addressbook, but I'm not finding any info about it in Google.
:(