I have been trying to find a way to navigate to navigate from an Application to the Settings preferences for the Application.
I have tried the following, yet unfortunately it does error.
var root = new UINavigationController ();
root.PushViewController (new Uri ("prefs:root=General"), true);
Sorry, you can't. Apple disabled the ability to do this in iOS 5.1.
The only option is creating your own preferences UI and displaying that instead.
Edit: as of iOS 8, you can take the user direct to your app's preferences: