Cross-media measurement is the “the holy grail” for TV audience researchers this upfront season, comScore Chief Revenue Officer Manish Bhatia says. And his company today is unveiling its version of the vessel: a collection of tools that it says now deliver “the first set of cross-media measurement data” tracking ad exposures across TV, radio, PCs, smartphones, and tablets.

ESPN had tested the service, formerly called Project Blueprint. But comScore has begun to deliver data to all of the major broadcast networks plus several major cable groups, it will tell researchers today at an NYC summit sponsored by the Coalition for Innovative Media Measurement — a programmer and advertiser supported group helping to develop digital age ratings tools.

That could be important for the upfront ad sales season: Rival Nielsen “to the best of our knowledge” doesn’t offer “the large scale of television data that we have,” says Bhatia. comScore’s sample base, he adds, is large enough to provide “granular data [about cross-platform viewing] at the program level.”

Nielsen will present its roadmap for cross-platform ratings later today at the CIMM summit.

CIMM chief Jane Clarke calls comScore’s announcement “a major industry milestone” that could help advertisers determine how to get the biggest bang for each buck they spend on media. “It’s hard to predict exactly how this will change the market, but at least they won’t complain that they don’t have the numbers.”

She adds that programmers receiving the comScore data “have been pleasantly surprised” by the number of viewers watching on digital media.

Companies receiving comScore data now include A&E Networks, CBS, Disney ABC Television Group, ESPN, Fox Networks, NBCUniversal, Scripps Networks, Univision, and Viacom.