// popView is the existing pop up view to be replaced
MyPopupViewController *newPopView = [[MyPopupViewController alloc] initWithData:...];
[UIView animateWithDuration:0.4
        delay:0
        options:UIViewAnimationOptionCurveEaseInOut
        animations: ^{
                   [self.view addSubView: newPopView.view];
                   [popView removeFromSuperView];
                   [UIView setAnimationTransition: UIViewAnimationTransitionCurlUp
                                          forView:popView cache:YES];
        } completion:^(BOOL finished) { popView = newPopView }
];
[newPopView release];