It seemed some-one goofed on the Altel website, and accidentally revealed the Altel HTC Touch Diamond on a HTC Touch page. The web page, which is not accessible from their front page, clearly shows an Altel-branded HTC Touch Diamond, but the details and 3D view shows only the older HTC Touch.
An associated rebate form does however talk about a rebate which needed to be handed in before 30 October. While the situation does remain confusing, it seems we can add the HTC Touch Diamond to the HTC Touch Pro as another device coming soon to the rural carrier.
See the web page in question here.