Not sure how the DVR could do that.
Even the Dish Hopper can only do it for certain prime time shows and it can't do it real time (their FAQ says it is not available until after 1 am ET).
Yeah, like all the advertisers aren't going to put pressure on the channels to prevent that from happening. Channels would start losing advertisers faster than you can say "Pass the popcorn!"
In fact, I had a VCR once that recorded the ads with the programing but sensed some signal that ads generated and, on playback, would fast forward past the ads. That no longer exists either.
Nice thought, but that ain't gonna happen!