Hi,
Iphone HIG Page 131 says this
It’s important to emphasize that the reason to supply a launch image is to improve user experience; it is not an opportunity to provide:
■ An “application entry experience,” such as a splash screen
■ An About window
■ Branding elements, unless they are a static part of your application’s first screen
Please verify what the last line mean. Is that like I can put my branding based image as launch image or not ?
It means that you can put branding in the launch image, but only when it's part of what the user will see after the application has launched. So if the branding is part of the actual interface, it's ok to have it as part of the launch image, but you can't put branding in the launch image that won't be visible in the application when the launch image dissapears.
It seems like Apple is ignoring this rule a lot, because more than half of the apps on my phone use the Default.png as a spash-screen, loading screen, etc.
You probably shouldn't use it for these things, though, because Apple may reject your app. But I don't really think it matters.