While Gmail has long placed ads at the very top of the Promotions and Social inboxes, it never dared to stick them in between messages. The new placement makes it even more confusing to distinguish between actual emails and ads, even if the promotions have the little green “Ad” icon placed next to them. It’s not clear if this is some kind of test or a gradual rollout. (I’m not seeing ads scattered within any of my inboxes just yet.)