I concur with bruin95, probably no earlier than 2009.
Dish still has 18 markets announced in January 2006 that have yet to be launched. Based on their satellite capacity and upcoming launches, the most likely future spot for Las Vegas HD locals would the Ciel 2 satellite currently scheduled to be launched to the 129 orbital location in late 2008.
As you're probably aware, Cox Cable and DirecTV carry Las Vegas HD locals now. Additionally, your Dish HD receiver has an OTA input. You MAY be able to receive HD locals from many areas within the Las Vegas valley with a VHF/UHF antenna. (I have to emphasize may because in practice KVBC-DT NBC HD is notoriously difficult to reliably receive.)
Thank you for the input. I do have OTA via 622 and 722, but I rarely can get NBC HD here in Anthem. I wish E would have some sort of timetable, at least an "official"projection. Cox and D are not a viable option for me at this time.