TiVo plans to provide a report for almost every national ad that it tracks. Data will include the number of people who saw the spot and when it was viewed. It also will offer measurements by program genre, the time of day the ad ran, network, day of week and an the ad's position in the commercial block.
Big-business media buffs probably wouldn't be satisfied with having to change their tactics, and likely will instead continue to try and “force” people to watch commercials. I doubt anyone would be happy with that, however.