maybe list U-Verse does it, with a conflict resolution dialog.
basically, "these conflict, which to you want to record?"
or, even better is the TiVo solution. every scheduled recording is put on a list from highest to lowest. if I move a show to the top, it just knows that's the most important thing, and it doesn't need to bother me to ask. I can move shows up and down in the list, and it takes the highest one over anything lower whenever there is a conflict. easy to see, easy to set up (for the user) and works great