I have a tab-based iPhone app where I want to increase the perceived start-up speed with a launch image. As defined by the iPhone HIG, the launch image is a screenshot of your app (called Default.png) that is displayed immediately and looks very similar to the app's first screen (e.g., the screenshot of an empty table when the app displays a table first).

Now the problem with a tab-based app is that users can rearrange the order of tabs so that any of the tabs may be the first tab to show upon launch. I think I read somewhere that you can't change the Default.png programmatically in your app, but I couldn't find that in the HIG (and the "Clock" app seems to do exactly that - having one launch image per tab).

So, how do provide a launch image for a tab-based app?