Google is testing a new knowledge graph interface for showing a timeline of data, facts and knowledge in the top carousel section of the Google search results.
Florian Kiersch spotted this first and captured a video of it, posting the video on Google+.
The timeline shows you data elements related to your search query. When you hover your mouse over the timeline, Google will show you tidbits of data. If you click on the element, Google will drill into the timeline of that element.
Here are some pictures:
Alex Chitu has more screen shots of this feature as well on his blog.