In a blow to Nielsen, the longtime predominant ad currency, the media conglomerate announced that it will activate iSpot.tv's cross-platform audiences as currency for national ad buys at this year's Upfront, according to Kelly Abcarian, executive vice president of measurement and impact at NBCU Advertising and Partnerships. Comscore will be the currency for local ad buys.

The challenge to that effort comes from the networks who have begun to create their own audience-measurement efforts using rivals such as iSpot, ComScore and VideoAmp, in hopes that advertisers will start moving some portion of their media buys to be graded by their alternatives.