I think the reason we've seen this phone, prior to an ipod with the same technologies, is the cost of the components involved. Particularly multi-touch, but the embedded processor and screen are much more expensive items than the previoous generation of ipods - and will have involved a large R&D cost.
it's quite possible that Apple couldn't bring these directly to the iPod in a cost competitive format. They may be leveraging the larger market, and price point, of this phone in order to be able to bring down costs for use in a "vPod".
Personally, I'm confident that there WILL be a further HD incarnation of the iPod, which incorporates some of this technology. However, I'm not certain that it will be in an immediate time frame, both for the reasons stated above and to avoid canibalizing iphone sales.
J