What amazes me about the HD from HDnet, as opposed to the networks, is just how much better it looks. They're really taking advantage of the broader dynamic range of HD, where the major networks have to produce a signal that can not only be cropped but also shoehorned into the more limited gamut of NTSC.

As Andy says, we'll at some point hit a switch when HD will be the default and SD will be less crucial. I figure the coming death of analog TV broadcasts will be one of the big steps along that particular path.