Just for the record, we too have the problem with PBS. For whatever reason they just can't seem to get it right. When switching resolutions, like during a break or between shows, the picture often blows up on return. For instance it often will not snap in at all while at other times it will shrink to the upper left quarter of the screen. I've communicated with them and they have no idea how to fix it. They also are having difficulty with their subs with the same set of problems. The assumption that TV technicians who have dealt with analog equipment all their lives would suddenly have digital expertise was, to say the least, overly optimistic.
In the Philadelphia area CBS has no subs while most of the other networks do although none of them are worth the effort. As someone said, it's often infomercials but just as often it's simply weather. In my opinion the real opportunity for subs is right there in front of NBC's face and they don't see it. I'm talking about the Olympics. Everyone, and I mean everyone, is complaining about the over-abundance of Beach Vollyball and preliminary heats in (you name it) while those sports people really want to see like baseball, softball, basketball etc. are virtually missing. Here was a golden opportunity to show what digital OTA is really capable of. Those NBC subs should be loaded with Olympic coverage but, sadly, they are not. What a waste.