Doubt it, too new technology.. even if it did, wouldn't they have to sell separate iTunes cables with 3.0 compatibility? Not completely 100% sure.. Oh well sounds good though if it does.
Apple wouldn't need to ship separate cables since the USB 3.0 standard implements backward compatibility with USB 2.0. So if Apple were to ship a USB-3.0-ready cable with the iPhone 4, we can still use it to connect our 2G/3G/3GS devices. We just won't be getting that wonderful high speed connectivity of USB 3.0, at least not until the iPhone has the hardware to support it.
I also doubt that we'll see such support anytime soon, at least not until the iPhone 5 or iPhone 6. Not to mention, the Mac product lines haven't yet been refreshed to include USB 3.0. I don't think Steve would be particularly happy with the notion of iPhone/MAC users being strapped because of USB technology, so it wouldn't make sense to include USB 3.0 with the iPhone 4 if Mac users can't take advantage of it.
No matter what, there's definitely a lot of exciting things to come.
