Why doesn't an iPhone app's main() function ever get a chance to finish?

Consider the following main() method which you would find most iPhone applications:

int main(int argc, char *argv[])
{
    NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
    int retVal = UIApplicationMain(argc, argv, nil, nil);
    [pool release];
    return retVal;
}

In every iPhone app that I've run in Simulator with these (including several sample projects provided by Apple), the thread never exits UIApplicationMain() and any remaining code in main() is never executed. Is this expected behavior?

I have verified that statements after UIApplicationMain() never run by stepping through the code with a debugger. When the user stops an application (by hitting the "Home" button, for example), the resulting stack trace shows that [UIApplication _terminateWithStatus:] is eventually called. This function calls your application delegate's applicationWillTerminate: method. Once that finishes, [UIApplication _terminateWithStatus:] seems to kill/exit the thread.

Can someone confirm that this is how main() is supposed to work, or at least confirm the same behavior on their machine?