Most cable companies and satellite providers have used their extra bandwidth to shove on more channels than to improve quality or add HD.
Look at the ads for Direct TV. They used to tout their better picture, but now that they have 500 channels the info is so compressed that they can't anymore.
CBS is the only network with consistent HD, but that I have to get with an antenna. Damn JAG looks good though. ABC has a couple things but their HD picture isn't as good, though when they showed Indiana Jones it looked awesome. NBC basically had the Olympics, which was taped delayed skating for the most part, and Jay Leno, both of which look(ed) great cause they are native HD, but that is it for programing. FOX doesn't even have true HD. They transmit in 480p which is like watching a DVD.
I'd at least like to see all the networks get on board soon. If more people saw what the picture looked like there would be much more demand and prices would come down even further. The picture they show in the stores does not do true HD justice.