I think we'll see a lot of providers using the 860Mhz-1ghz spectrum for MPEG4 video until all the set tops are capable of doing MPEG4. That could take a while.
My guess is the 750MHz-1GHz spectrum. Systems that don't have more than 750 MHz are more more likely to be upgraded sooner. The approximately 450 MHz used for analog will also be nearly cut in half.
