A recent Google research project found that 80% of searches on smartphones are spontaneous, as opposed to planned, and nearly half of those are goal-oriented. Often those goals are purchases and, to Jonathan Alferness, this is evidence of mobile's role as a bridge -- and an extremely valuable one -- from the digital world to the physical one.

"We're starting to drive meaningful value that wasn't possible on desktop," said Mr. Alferness, director of product management-mobile ads lead at Google, in a recent interview. "We're driving users to actual, physical retail stores to buy something. "

Mr. Alferness, who will be speaking at Ad Age 's Digital Conference later this month, is an eight-year veteran of Google, having spent a lot of that time on its syndicated products and on its desktop search ad business. In his current role, he sees his central priority as "showing to advertisers full value of mobile."

There have been successes, one of which is Google's Click-to-Call ad product, which seeks to put consumers on the phone line with advertisers. But many big challenges loom. "What's not being done is finding ways to encapsulate all the value being unlocked in mobile and showing that to advertisers," he said.

To illustrate, he points to desktop search, which in its early days demonstrated its value through all the e-commerce transaction that came through Google Adwords. While Mr. Alferness says that mobile commerce is also a big deal, it's "a small portion of the overall value users are getting."

One thing that has to happen is a better understanding of when mobile is driving sales in-store, when the retailers can be certain that a customer entered the purchase funnel through mobile search.

"That's the holy grail," he said.