It turns out that the HTC Diamond's lack of support for the US bands we need to use the thing reliably may not be a hardware limitation. wmpoweruser [via] has unearthed this thread from XDA that includes a new Radio ROM. See -- there's the ROM for your smarpthone and a separate ROM for the radio. This new ROM enables support for the 850 band for EDGE, meaning the Diamond has suddenly become a viable (though EDGE-only) phone for most of the US!
Those readers have some cause to rejoice - an updated Radio ROM (V100.25.05) leaked by XDA-Developers hackers manages to activate the hidden 850 Mhz radio, allowing GSM and EDGE connectivity to work on all the GSM networks in USA. Unfortunately there is still no support for US 3G, but one is left only to wonder whether this is very far behind, seeing how HTC is planning to release the HTC Touch Diamond on the Australian Telstra network, which uses the same 3G bands as AT&T. - wmpoweruser
Indeed, if the enterprising hackers at XDA can unlock EDGE's 850 band, mayhap they can get this battlestation fully operational here in the US sooner than the rebel alliance, er, HTC does!