From Sioux City I have picked up 3 channels from Nebraska Public TV - for one day. I think they were running tests. Each channel had different programming - as I recall there were two different episodes of Charlie Rose and something else.
Of course, the signal from Vermillion SD is pretty strong: 2.1 is PBS digital and 2.2 is their "regular" analog signal re-broadcast in digital. IPTV is on 27.1 with mostly the same PBS digital.
I can receive the HD signals from the Sioux Falls CBS and ABC, and I expect to be able to receive the NBC feed very soon -- as soon as KDLT ups their signal strength.
Locally in Sioux City, KTIV, KCAU and KMEG all put out signals powered by a Duracell battery, and only KTIV is in HD. KTIV is negotiating with CableOne to put their HD signal on the wire, but nothing is certain there.
The unfortunate truth is that we're on the bleeding edge of the HD revolution, and in a smaller market we should be happy (thrilled, even!) to get a test pattern.
In theory there is no difference between theory and practice. But in practice there is.