I totally agree. A DTV app would be great. the current mobile site does not take any advantage of the iPhone's capabilities. Even a specific website for iPhones would be useful. trying to do a DTV scheduled record via the current mobile site is not as easy as it should be. The scrolling channel line up on the non-mobile site is much better and could be adapted for the iPhone.
Then there's the idea that they could make a great app for the iPhone too. One that, when used at home (with a networked receiver) could be used to search the guide, change channels, manage recordings, etc. Basically another interface into your DVR/receiver without having to use the TV remote. This could be useful in SO many different places, especially in commercial establishments with multiple receivers.