At Google I/O yesterday, Google first announced updates to how they will handle top stories in the search results. Google showed how the top stories has a new top filter bar to let you learn more about a topic, see that stories timeline, and even hear podcasts that you can play about that topic. They call this "full coverage" that shows you more about the story's topic than just the top stories.
Here is a screen shot I took from the live stream which starts at 4:40 mark into the video:
Timeline:
Podcasts where Google searches the actual audio of the podcast and lets you listen to it or save to listen to it later.
Here is the video embed at the start time:
Full coverage in top stories is coming later this year according to Sundar Pichai.
Forum discussion at Twitter.