Are there mounted volumes on the iPhone / iPad? How to use these?

NSFileManger has this method:

- (NSArray *)mountedVolumeURLsIncludingResourceValuesForKeys:(NSArray *)propertyKeys options:(NSVolumeEnumerationOptions)options

the docs say it's for iOS 4.0; That sounds interesting. So I can plug in an USB stick now some time soon? Or can I do so already via the 30-pin connector (if I had a fancy adapter)?

Do you know of some real life us开发者_高级运维e cases for this? I'm playing with low level file stuff around right now, and I'm curious as of what I could do with mounted volumes.

If you use the camera connection kit, it's possible that plugged-in cameras count as mounted volumes. That's the only thing I can think of that would cause a mounted volume on an iOS device.