In the iPad Programming Guide, it gives the following code example for specifying the two views (firstVC and secondVC) that will be used in the SplitView...

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
   MyFirstViewController* firstVC = [[[MyFirstViewController alloc]
                     initWithNibName:@"FirstNib" bundle:nil] autorelease];
   MySecondViewController* secondVC = [[[MySecondViewController alloc]
                     initWithNibName:@"SecondNib" bundle:nil] autorelease];

   UISplitViewController* splitVC = [[UISplitViewController alloc] init];
   splitVC.viewControllers = [NSArray arrayWithObjects:firstVC, secondVC, nil];

   [window addSubview:splitVC.view];
   [window makeKeyAndVisible];

   return YES;
}

but when I actually create a new SplitView project in Xcode, I don't see any code that specifies which views should be added to the SplitView. Here's the code from the SplitView template...

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {    

    // Override point for customization after app launch    
    rootViewController.managedObjectContext = self.managedObjectContext;


    // Add the split view controller's view to the window and display.
    [window addSubview:splitViewController.view];
    [window makeKeyAndVisible];

    return YES;
}

Thanks in advance for all your help! I'm going to continue researching this question right now.