Starting with iOS 5, there are two notification styles: banner and alert (the \"old\" style). A user can set which style to use for each application in the settings. However
have you tried
[[UIApplication sharedApplication] registerForRemoteNotificationTypes: (UIRemoteNotificationTypeBadge | UIRemoteNotificationTypeSound)];
in your didFinishLaunching method, this won't help those updating but should enable alerts for those first installing