IAB President Randall Rothenberg opened the 2nd Annual Podcast Upfront acknowledging there are questions to be answered and that “marketers and advertisers worry." Among their concerns: What is this new medium? How do we navigate and how do we measure? What acquisition tactics will marketers use to grab share of ear? But, he promised, “With some 50 million monthly listeners of podcasts we’ve passed our ‘Serial’ moment.” It may be the nature of a nascent platform -- as all team up to figure it out and evolve together -- but for a medium approaching critical mass it is time to deliver specifics to a hungry ad community.