The iPad has a storage mode, supposedly, for some portion of the iPad's file system. I'm not sure of the details, I just remember that it was part of the feature list (that you can use it as a general/generic USB storage device, for a _portion_ of its capacity).

But, I was talking more about the other way around: the ability to use USB storage devices (generally, not just the SD card reader dongle). I expect that it can already do that, because of the camera kit having both an SD card reader AND a USB port for USB sync'ing cameras. But it isn't documented what all of the USB devices are that it supports.

It may be that #1 is basically already true (if the USB Host port dongle in the camera kit can work with all storage devices, keyboards, and maybe mice and modems). It just might not be fully documented and fully supported. That's what I'd want (partially so that it can't be removed later). Plus, I'd want to see similar support on the iPhone and iPod Touch. Though, that might require a new dock connector for those two devices.

However, yes, also being able to use the iPhone, iPod Touch, and iPad as a USB storage device, for a portion of the file system that does not contain things like the OS, and DRM'ed/managed/etc. files, would be nice as well.