Google is “currently running a limited test in which a small number of users are seeing ads that are marked based on signals related to quality and relevance. This experiment is part of our ongoing efforts to help users find what they’re looking for, and we’re closely monitoring feedback.”
The new ad format has “featured ads” within the ad units, with little yellow stars next to them. And if you mouse over the star, it using a title attribute that reads “Featured Ad.” here is a screen capture:
